Research on fathering and the father-child relationship has made substantial progress in the most recent 15 years since the last special issue of the Infant Mental Health Journal on fathers and young children. This special issue on fathers and young children contains a series of papers exemplifying this progress, including advances in methodology-more direct assessment and more observational measures-in addition to the increasing dynamic complexity of the conceptual models used to study fathers, the diversity of fathers studied, and the growth of programs to support early father involvement. In assessing the current state of the field, special attention is given to contributions made by the papers contained in this special issue, and two critical areas for continued progress are addressed: (1) methodological and measurement development that specifically address fathers and fathering relationships and (2) cross-cultural and ecologically valid research examining the diversity of models of fathering.