The year 2004 marked the fiftieth anniversary of the Merrill-Palmer Quarterly: A Journal of Developmental Psychology, providing an occasion to celebrate the journal's heritage and its long history of scholarly contributions to its field. This volume celebrates this milestone by bringing together twenty-three distinguished essays that showcase past accomplishments, current progress, and future challenges in the human developmental sciences. The essays presented in this volume offer perspectives on many of the research domains and specialty areas that have been prominent in MPQ's history. Accordingly, chapters are organized around ten conceptual themes, including methodological and interpretive considerations, cognitive development and learning, temperament and emotional development, children's social development and peer relations, family relations, moral development, the nature-nurture debate and behavioral genetics, cultural psychology, early child care and school-readiness, and evidence-based programming and public policy. In addition, an introductory chapter provides a historical overview of MPQ, examining the events, persons, institutional forces, and publication trends that brought the journal into existence and have contributed to its success and longevity. These commentaries are accessible and of interest to all who work with infants, children, adolescents, and families. As a result, this volume will appeal to researchers and professionals alike.