It is a general feature of molecular chaperones that they are highly conserved throughout evolution. Prokaryotic and eukaryotic Hsp70 proteins, for example, are over 50% identical at the amino acid level. The DnaJ family of molecular chaperones, however, share this conservation only within a single 70 amino acid domain called the J domain, and outside of this region the family is greatly divergent. Such diversification probably contributes to the varied actions of molecular chaperones in protein dynamics, from folding of nascent polypeptide chains to clathrin uncoating. DnaJ proteins function as part of the Hsp70 chaperone machine, since the J domain is known to stimulate the ATPase activity of Hsp70 proteins. This review will concentrate on recent progress in DnaJ research. Readers who are new to the field are encouraged to read previous reviews on the family by Caplan et al 1993; Silver and Way 1993, and Cyr et al 1994.