Ghosh, Rachel AlinaParenting practices and parent-child relationship quality, shaped in part by parenting cognitions and beliefs, have a strong proximal contribution to the course and outcome of children’s development from early in the lifespan. However, much existent empirical knowledge about parenting comes from studies of White middle-class mothers and children, and there is far less evidence from racially, ethnically, and economically diverse families – especially from fathers. Through a collection of three interrelated studies, the present dissertation contributes to this literature with an examination of fathers’ parenting motivations, and mothers’ and fathers’ independent and interactive influences on child and adolescent socioemotional outcomes among diverse families. Empirical Paper 1 qualitatively explored what motivated first-time Latino fathers in the U.S. to be good parents for their infants, and examined differences in their motivations by nativity status. Fathers described five primary themes, with variation by nativity,in their parenting motivations: 1) personal rearing history, 2) desire to rear a well-adjusted child, 3) relationship with their child, 4) intrinsic motivations, and 5) sense of duty and responsibility. Empirical Paper 2 examined associations between mothers’ and fathers’ quality of play (i.e., challenging parenting behaviors, playfulness) at 18 months and toddlers’ social competence at 24 months, and tested whether child negative emotional temperament moderated these associations. Contrary to hypotheses, there were no significant associations between mothers’ or fathers’ two types of play and children’s social competence, and no significant moderation effects by negative emotionality. Empirical Paper 3 examined the interactive effects of adolescents’ level of support in their relationships with mothers, fathers, and best friends in the 8th grade and associations with depressive symptoms, anxiety symptoms, and externalizing problems in the 9th grade, as well as differences by adolescent sex. There were several interactive effects of the relationships on later depressive symptoms, though not on anxiety symptoms or externalizing problems, and few differences by adolescent sex. More support from one parent was related to fewer depressive symptoms when youth experienced an unsupportive relationship with the other parent or with a best friend. Taken together, the findings of these studies advance developmental theory and provide nuance to our understanding of mothering, fathering, and children’s and adolescents’ socioemotional developmental processes. These studies have implications for research and programs aimed at promoting the normative, healthy development of diverse youth through recognizing and capitalizing on the contributions of different members within the family system.enDissertationDevelopmental psychologyIndividual & family studiesadolescenceearly childhoodfathersmothersmotivationplay