This essay investigates historical and philosophical questions about thc conccpts of developmental constraint and cvolvability. The conccpt 0f constraint was central for dcvclopmcntal approaches t0 cv01ution in thc 1980s but faded into thc background throughout thc 1990s, sccmingly rcplaccd by more important notions, such as cvolvability (Section 1). The historical part of my discussion presents two divcrging accounts as t0 why thc conccpt of developmental constraint ccdcd t0 thc concept of cvolvability. Onc thc first 0nc, thc conccpt 0f constraint was used t0 criticize adaptationism but did not undcrwritc cvolutionary explanations, and thus was rcplaccd by thc conccpt 0f cvolvability which in contrast provides a positive cxplanatory project (Section 2). Onc thc sccond historical account, thc conccpt of constraint has always bccn part 0f a positive cxplanatory project in cvolution and thus is in continuity with thc notion 0f cvolvability (Section 3). Thcrc is somc truth t0 both of thcsc historical stories, yct thc sccond 0nc turns out t0 bc historically more adequate and intellectually more revealing than thc first. The two accounts offcr 21 different portrayal 0f how thc concept of constraint was understood and cmploycd, so that my historical discussion is t0 primarily shcd light 011 thc concept of developmental constraint.