This issue on fathers was conceived as a rallying cry for all professionals to examine their practices of including fathers in their services. For too long, infant mental health professionals have either ignored fathers' important influences on infants and toddlers or have given lip-service to their importance while allowing the status quo of not including fathers to continue. This article provides history and context for the impetus behind--and the hurdles to--moving from focusing on dyads to family systems, and it highlights a few forward-looking new programs and initiatives already transforming practice. It sounds a clarion call for all professionals to dramatically alter the way they deal with fathers and families in the practice of infant mental health, and to begin doing so now.