UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549


                                  SCHEDULE 13D


                    Under the Securities Exchange Act of 1934
                              (Amendment No. 10 )*


                               DONEGAL GROUP INC.
                               ------------------
                                (Name of Issuer)


                          Common Stock, $1.00 par value
                         ------------------------------
                         (Title of Class of Securities)

                                   257701 10 2
                                 --------------
                                 (CUSIP Number)

 Ralph G. Spontak, Senior Vice President, Chief Financial Officer and Secretary
                        Donegal Mutual Insurance Company
                  1195 River Road, Marietta, Pennsylvania 17547

                                 (717) 426-1931
           -----------------------------------------------------------
           (Name, Address and Telephone Number of Person Authorized to
                      Receive Notices and Communications)

                                December 31, 1999
             -------------------------------------------------------
             (Date of Event which Requires Filing of this Statement)


If the filing person has previously filed a statement on Schedule 13G to report
the acquisition which is the subject of this Schedule 13D, and is filing this
schedule because of Rule 13d-1(e), 13d-1(f) or 13d-1(g), check the following
box |_|.

Note: Schedules filed in paper format shall include a signed original and five
copies of the schedule, including exhibits. See Rule 13d-7(b) for other parties
to whom copies are to be sent.

*The remainder of this cover page shall be filled out for a reporting person's
initial filing on this form with respect to the subject class of securities, and
for any subsequent amendment containing information which would alter
disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed
to be "filed" for the purpose of Section 18 of the Securities Exchange Act of
1934 ("Act") or otherwise subject to the liabilities of that section of the Act
but shall be subject to all other provisions of the Act (however, see the
Notes).

                                                              Page 1 of 11 pages

SCHEDULE 13D - ------------------------- -------------------------- CUSIP No. 257701 10 2 Page 2 of 11 Pages - ------------------------- -------------------------- - -------------------------------------------------------------------------------- 1 | NAME OF REPORTING PERSON | S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON (entities only) | | Donegal Mutual Insurance Company | I.R.S. I.D. No. 23-1336198 - -------------------------------------------------------------------------------- | 2 | CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (See Instructions) | N/A | (a) ____ | (b) ____ - -------------------------------------------------------------------------------- 3 | SEC USE ONLY | - -------------------------------------------------------------------------------- 4 | SOURCE OF FUNDS (See Instructions) | | 00 - -------------------------------------------------------------------------------- 5 | CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT | TO ITEMS 2(d) OR 2(e) |_| | N/A - -------------------------------------------------------------------------------- 6 | CITIZENSHIP OR PLACE OF ORGANIZATION | | Pennsylvania - -------------------------------------------------------------------------------- | 7 | SOLE VOTING POWER | | | | 5,249,324.768 shares NUMBER OF SHARES |-----|-------------------------------------- BENEFICIALLY | 8 | SHARED VOTING POWER OWNED BY EACH | | REPORTING PERSON | | N/A WITH |-----|-------------------------------------- | 9 | SOLE DISPOSITIVE POWER | | | | 5,249,324.768 shares |-----|-------------------------------------- | 10 | SHARED DISPOSITIVE POWER | | | | N/A - -------------------------------------------------------------------------------- 11 | AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON | 5,249,324.768 shares - -------------------------------------------------------------------------------- 12 | CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN | SHARES (See Instructions) | N/A |_| - -------------------------------------------------------------------------------- 13 | PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) | | 62.1% - -------------------------------------------------------------------------------- 14 | TYPE OF REPORTING PERSON (See Instructions) | | IC HC - --------------------------------------------------------------------------------

Page 3 of 11 Pages Item 3. Source and Amount of Funds or Other Consideration. Item 3 is hereby supplemented as follows: On February 16, 1999, Donegal Mutual Insurance Company ("DMIC") purchased 32,421.221 shares of Donegal Group Inc. ("DGI") Common Stock pursuant to the DGI Dividend Reinvestment Plan at a price of $12.525 per share, representing the average of the closing prices of DGI Common Stock on February 9, 10, 11, 12 and 15, 1999 for a total cost of $406,076. Between March 31, 1999 and May 17, 1999, DMIC, pursuant to its publicly announced program of purchasing DGI Common Stock from time to time in the Nasdaq National Market at prevailing market prices pursuant to SEC Rule 10b-18 and in privately negotiated transactions, made the following purchases of DGI Common Stock in the Nasdaq National Market: Number of Shares Per Share Aggregate Date of Purchase Purchased Purchase Price Purchase Price - ---------------- --------- -------------- -------------- March 31, 1999 1,000 $12.75 $ 12,750 April 1, 1999 12,000 11.83 141,960 ------ -------- 13,000 $154,710 ====== ======== On May 17, 1999, DMIC purchased 37,145.877 shares of DGI Common Stock pursuant to the DGI Dividend Reinvestment Plan at a price of $12.00 per share, representing the average of the closing prices per share of DGI Common Stock on May 10, 11, 12, 13 and 14, 1999, for a total cost of $445,751. Between May 20, 1999 and August 16, 1999, DMIC, pursuant to its publicly announced program of purchasing DGI Common Stock from time to time in the Nasdaq National Market at prevailing market prices pursuant to SEC Rule 10b-18 and in privately negotiated transactions, made the following purchases of DGI Common Stock in the Nasdaq National Market:

Page 4 of 11 Pages Number of Shares Per Share Aggregate Date of Purchase Purchased Purchase Price Purchase Price - ---------------- --------- -------------- -------------- May 20, 1999 1,000 $11.625 $11,625 May 24, 1999 1,000 11.125 11,125 June 1, 1999 1,000 10.625 10,625 June 3, 1999 1,000 10.500 10,500 June 8, 1999 1,000 10.500 10,500 June 11, 1999 5,000 11.250 56,250 June 16, 1999 1,000 10.625 10,625 June 25, 1999 1,000 10.875 10,875 June 30, 1999 1,000 11.125 11,125 ------ -------- 13,000 $143,250 ====== ======== On August 16, 1999, DMIC purchased 44,080.647 shares of DGI Common Stock pursuant to the DGI Dividend Reinvestment Plan at a price of $10.188 per share, representing the average of the closing prices per share of DGI Common Stock on August 9, 10, 11, 12 and 13, 1999, for a total cost of $449,094. Between August 17, 1999 and November 15, 1999, DMIC, pursuant to its publicly announced program of purchasing DGI Common Stock from time to time in the Nasdaq National Market at prevailing market prices pursuant to SEC Rule 10b-18 and in privately negotiated transactions, made the following purchases of DGI Common Stock in the Nasdaq National Market:

Page 5 of 11 Pages Number of Shares Per Share Aggregate Date of Purchase Purchased Purchase Price Purchase Price ---------------- --------- -------------- -------------- August 17, 1999 1,000 $10.125 $10,125 August 17, 1999 5,000 10.1875 50,938 August 18, 1999 1,000 9.9375 9,938 August 25, 1999 1,000 10.125 10,125 August 25, 1999 5,000 10.125 50,625 September 1, 1999 1,000 9.625 9,625 September 2, 1999 6,500 9.96875 64,797 September 3, 1999 1,000 9.9687 9,969 September 10, 1999 1,000 9.875 9,875 October 5, 1999 1,000 9.50 9,500 October 7, 1999 6,000 9.625 57,750 October 8, 1999 1,000 9.50 9,500 October 12, 1999 1,000 9.6875 9,688 October 13, 1999 1,000 9.25 9,250 October 14, 1999 1,000 9.125 9,125 October 21, 1999 1,000 9.00 9,000 October 22, 1999 1,000 8.875 8,875 October 27, 1999 1,000 8.750 8,750 October 29, 1999 1,000 8.6875 8,688 November 1, 1999 1,000 7.875 7,876 November 2, 1999 1,000 8.125 8,125 November 3, 1999 1,000 7.875 7,875 November 4, 1999 1,000 7.875 7,875 November 5, 1999 6,500 7.875 51,188 ------ -------- 48,000 $449,082 ====== ======== On November 15, 1999, DMIC purchased 57,714.765 shares of DGI Common Stock pursuant to the DGI Dividend Reinvestment Plan at a price of $7.85 per share, representing the average of the closing prices per share of DGI Common Stock on November 8, 9, 10, 11 and 12, 1999, for a total cost of $453,061. Between November 17, 1999 and December 31, 1999, DMIC, pursuant to its publicly announced program of purchasing DGI Common Stock from time to time in the Nasdaq National Market at prevailing market prices pursuant to SEC Rule 10b-18 and in privately negotiated transactions, made the following purchases of DGI Common Stock in the Nasdaq National Market:

Page 6 of 11 Pages Number of Shares Per Share Aggregate Date of Purchase Purchased Purchase Price Purchase Price ---------------- --------- -------------- -------------- November 17, 1999 7,000 $ 7.5625 $ 52,938 November 18, 1999 1,000 7.375 7,375 November 19, 1999 1,000 7.50 7,500 November 24, 1999 1,000 7.3125 7,313 November 29, 1999 7,000 6.875 48,125 December 2, 1999 1,000 6.75 6,750 December 3, 1999 1,000 6.25 6,250 December 6, 1999 1,000 6.625 6,625 December 7, 1999 1,000 6.50 6,500 December 8, 1999 1,000 6.3125 6,313 December 9, 1999 9,000 6.257 56,313 December 10, 1999 1,000 7.125 7,125 December 13, 1999 1,000 7.625 7,625 December 15, 1999 1,000 7.375 7,375 December 16, 1999 1,000 6.9375 6,938 December 17, 1999 1,000 6.625 6,625 December 20, 1999 1,000 6.675 6,675 December 21, 1999 9,500 6.467 61,437 December 22, 1999 9,000 6.514 58,626 December 23, 1999 9,100 6.194 56,365 December 27, 1999 1,000 6.375 6,375 December 28, 1999 9,000 6.7986 61,187 December 29, 1999 1,000 6.625 6,625 December 30, 1999 1,000 6.5625 6,563 December 31, 1999 1,000 6.4375 6,438 December 31, 1999 8,000 6.4375 51,500 ------ -------- 85,600 $569,480 ====== ======== All of the purchases by DMIC described herein were made with funds derived from DMIC's working capital or from dividends received from DGI. Item 5. Interest in Securities of the Issuer. Item 5 is hereby supplemented and restated in its entirety as follows:

Page 7 of 11 Pages (a) As of December 31, 1999, the following persons and entity beneficially owned the number of shares of Common Stock of DGI set forth opposite their respective names: Shares Percent of Name of Individual Beneficially Outstanding or Identity of Group Owned(1) Common Stock(2) -------------------- ------------- --------------- 5% Holders: Donegal Mutual Insurance Company...................................... 5,249,324.768 62.1% 1195 River Road Marietta, Pennsylvania 17547 Directors of DGI: C. Edwin Ireland...................................................... 20,086(4) -- Donald H. Nikolaus.................................................... 317,988(5) 3.7% Patricia A. Gilmartin................................................. 11,551(4) -- Philip H. Glatfelter, II.............................................. 13,979(4) -- R. Richard Sherbahn................................................... 9,598(4) -- Robert S. Bolinger.................................................... 11,310(4) -- Thomas J. Finley, Jr.................................................. 10,220(4) -- Executive Officers of DMIC and DGI (3): Ralph G. Spontak...................................................... 126,662(6) 1.5% William H. Shupert.................................................... 57,267(7) -- Frank J. Wood......................................................... 43,519(8) -- Robert G. Shenk....................................................... 49,444(9) -- Cyril J. Greenya...................................................... 42,076(10) -- James B. Price........................................................ 47,356(11) -- Daniel J. Wagner...................................................... 36,950(12) -- Directors of DMIC (13): Frederick W. Dreher................................................... 25,403(4) -- John E. Hiestand...................................................... 10,703(4) -- - ------------------- (1) Information furnished by each individual named. This table includes shares that are owned jointly, in whole or in part, with the person's spouse, or individually by his spouse.

Page 8 of 11 Pages (2) Less than 1% unless otherwise indicated. (3) Excludes Executive Officers listed under "Directors of DGI." (4) Includes 8,889 shares of DGI Common Stock the director has currently exercisable options to purchase under DGI's 1996 Equity Incentive Plan for Directors. (5) Includes 222,222 shares of DGI Common Stock Mr. Nikolaus has currently exercisable options to purchase under DGI's Amended and Restated 1996 Equity Incentive Plan (the "1996 Equity Incentive Plan"), but excludes (i) 44,445 shares he has the option to purchase after July 1, 2000, (ii) 33,333 shares he has the option to purchase after December 16, 2000, (iii) 33,334 shares he has the option to purchase after December 16, 2001 and (iv) 33,333 shares he has the option to purchase after December 16, 2002. (6) Includes 106,666 shares of DGI Common Stock Mr. Spontak has currently exercisable options to purchase under the 1996 Equity Incentive Plan, but excludes (i) 20,000 shares he has the option to purchase after July 1, 2000, (ii) 13,333 shares he has the option to purchase after December 16, 2000, (iii) 13,334 shares he has the option to purchase after December 16, 2001 and (iv) 13,333 shares he has the option to purchase after December 16, 2002. (7) Includes 50,666 shares of DGI Common Stock Mr. Shupert has currently exercisable options to purchase under the 1996 Equity Incentive Plan, but excludes (i) 6,667 shares he has the option to purchase after July 1, 2000, (ii) 3,333 shares he has the option to purchase after December 16, 2000, (iii) 3,334 shares he has the option to purchase after December 16, 2001 and (iv) 3,333 shares he has the option to purchase after December 16, 2002. (8) Includes 40,889 shares of DGI Common Stock Mr. Wood has currently exercisable options to purchase under the 1996 Equity Incentive Plan, but excludes (i) 8,889 shares he has the option to purchase after July 1, 2000, (ii) 3,333 shares he has the option to purchase after December 16, 2000, (iii) 3,334 shares he has the option to purchase after December 16, 2001 and (iv) 3,333 shares he has the option to purchase after December 16, 2002. (9) Includes 44,445 shares of DGI Common Stock Mr. Shenk has currently exercisable options to purchase under the 1996 Equity Incentive Plan, but excludes (i) 7,111 shares he has the option to purchase after July 1, 2000, (ii) 8,333 shares he has the option to purchase after December 16, 2000, (iii) 8,334 shares he has the option to purchase after December 16, 2001 and (iv) 8,333 shares he has the option to purchase after December 16, 2002. (10) Includes 40,889 shares of DGI Common Stock Mr. Greenya has currently exercisable options to purchase under the 1996 Equity Incentive Plan, but excludes (i) 7,111 shares he has the option to purchase after July 1, 2000, (ii) 5,333 shares he has the option to purchase

Page 9 of 11 Pages after December 16, 2000, (iii) 5,334 shares he has the option to purchase after December 16, 2001 and (iv) 5,333 shares he has the option to purchase after December 16, 2002. (11) Includes 40,889 shares of DGI Common Stock Mr. Price has currently exercisable options to purchase under the 1996 Equity Incentive Plan, but excludes (i) 7,111 shares he has the option to purchase after July 1, 2000, (ii) 5,333 shares he has the option to purchase after December 16, 2000, (iii) 5,334 shares he has the option to purchase after December 16, 2001 and (iv) 5,333 shares he has the option to purchase after December 16, 2002. (12) Includes 26,666 shares of DGI Common Stock Mr. Wagner has currently exercisable options to purchase under the 1996 Equity Incentive Plan, but excludes (i) 4,444 shares he has the option to purchase after July 1, 2000, (ii) 3,333 shares he has the option to purchase after December 16, 2000, (iii) 3,334 shares he has the option to purchase after December 16, 2001 and (iv) 3,333 shares he has the option to purchase after December 16, 2002. (13) Excludes Directors listed under "Directors of DGI" and "Executive Officers of DMIC and DGI." (b) All of the persons together with his or her spouse and the entity described in Item 5(a) have sole voting power and sole dispositive power over all of the shares described in Item 5(a). (c) Reference is made to Item 3 hereof. To the best knowledge of DMIC, none of the persons named in Item 5(a) hereof has purchased or disposed of any shares of DGI Common Stock during the 60 days preceding December 31, 1999, except (i) purchases pursuant to the DGI Dividend Reinvestment Plan, (ii) purchases pursuant to the DGI Employee Stock Purchase Plan, (iii) the purchases by DMIC in the Nasdaq National Market reflected in Item 3 hereof and (iv) the following purchases in Nasdaq National Market transactions by the persons listed in Item 5(a) hereof: Aggregate Number of Per Share Purchase Name of Purchaser Date of Purchase Shares Purchased Purchase Price Price - ----------------- ---------------- ---------------- -------------- ------------- Donald H. Nikolaus December 2, 1999 500 $6.25 $3,125 Donald H. Nikolaus December 2, 1999 500 6.38 3,188 Donald H. Nikolaus December 3, 1999 300 6.50 1,950 Donald H. Nikolaus December 3, 1999 200 6.38 1,275 Donald H. Nikolaus December 23, 1999 1,000 6.13 6,125 Donald H. Nikolaus December 27, 1999 1,000 6.25 6,250 Donald H. Nikolaus December 28, 1999 3,000 6.50 19,500 Donald H. Nikolaus December 29, 1999 500 6.38 3,188 Donald H. Nikolaus December 29, 1999 500 6.31 3,155

Page 10 of 11 Pages Donald H. Nikolaus December 29, 1999 2,000 6.50 13,000 Donald H. Nikolaus December 30, 1999 1,000 6.38 6,375 Donald H. Nikolaus December 31, 1999 2,000 6.38 12,750 Donald H. Nikolaus December 31, 1999 3,876 5.42 21,003 Philip H. Glatfelter, II December 1, 1999 500 7.00 3,500 Philip H. Glatfelter, II December 2, 1999 300 6.38 1,913 Daniel J. Wagner December 29, 1999 10,000 6.50 65,000

Page 11 of 11 Pages SIGNATURE After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this Statement is true, complete and correct. DONEGAL MUTUAL INSURANCE COMPANY By: /s/ Ralph G. Spontak ---------------------------------------- Ralph G. Spontak, Senior Vice President, Chief Financial Officer and Secretary Dated: January 19, 2000