This volume has grown out of a conference on the theme “Language acquisition and conceptual development,” which was held at the Max Planck Institute for Psycholinguistics in November 1995. The conference was an unusually stimulating and exciting meeting, where intellectual positions were on the brink of change. We hope that this volume captures some of that excitement about theory change in the making.

The program was devised by the editors of this volume in collaboration with Dan Slobin and Wolfgang Klein. All the papers delivered on that occasion are reprinted here, but with substantial revisions that take account of each other and the discussion at the conference. Part of that discussion was provided by commentators on each session, and we thank Shanley Allen, Martha Crago, Eve Danziger, Eric Pederson, and DavidWilkins for their probing comments, comparisons, and substantial ideas, now partly woven into the fabric of the chapters. Differences in length between the chapters stem in part from the different roles of the papers in the original conference, and in part from constraints on the size of this volume.

We thank the Max Planck Society for sponsoring the conference, and the support staff of the Max Planck Institute for Psycholinguistics for their help.We especially thank Edith Sjoerdsma for her invaluable help in organizing the conference and collating the volume.

One of the participants at the conference was Martin Braine, who died a few months after the meeting.