Noting that the research literature about father involvement is expanding at an exponential rate, this paper explores seminal ideas about father involvement in families. The paper is presented in three parts. The first part provides an overview of the emerging research on social fatherhood. This part traces the changes in the concept of fatherhood from a simple two-variable model (i.e., father absence has a negative influence on children) to the more sophisticated constructs of father involvement that focus on how fathers enact the parenting role. The second part of the paper explores compelling lines of research that relate to several primary features of father involvement, such as the contexts of interaction, father's motivations, and the mechanisms of enactment. The third part presents a short overview of family process ideas. Future research directions are suggested, and calls for more systematic theory building around the fathering role. (Contains 157 references.) (Author/KB)