Connectionist networks that have learned one task can be reused on related tasks in a process that is called 'transfer'. This paper surveys recent work on transfer, and includes an overview of the articles in this volume. A number of distinctions between kinds of transfer are identified, and future directions for research are explored. The study of transfer has a long history in cognitive science. Discoveries about transfer in human cognition can inform applied efforts. Advances in applications can also inform cognitive studies.