It is proved in this paper that for m 0; 2; 6; 10 (mod 12) there exists a resolvable group divisible design of order v, block size 4 and group size m if and only v 0 (mod 4), v 0 (mod m), v - m 0 (mod 3), except when (3; 12) and except possibly when (3; 264); (3; 372); (8; 80); (8; 104), (9; 396) (40; 400) or (40; 520). c 2002 Elsevier Science B.V. All rights reserved.