In North American sunfishes (Lepomis: Centrarchidae) ♂♂ build nests and provide solitary parental care for the young. In this paper I provide for bluegill (L. macrocbirus) a detailed account of ♂♂ which do not build nests, but steal fertilizations from the nests of other ♂♂. I begin by giving data on the behavior, morphology, and population demography of ♂♂. Next, through an analysis of individual male life-histories, I show that cuckoldry and parenting are discrete alternative reproductive strategies. This is followed by a theoretical analysis and an empirical test of cuckoldry and parental care as evolutionarily stable strategies (a mixed ESS). Several predictions are made concerning how natural selection will influence the life-history dynamics of these strategies. A general theory is then developed for sunfishes, and a first test made on the pumpkinseed (L. gibbosus). Finally, I note the parallels between male cuckoldry in sunfishes and precocial male life-histories in salmon and cichlids.