Objective: A multidisciplinary preventive parent mentoring intervention was applied through home visiting with high-risk families receiving well-baby health care. Two implementations were examined for effectiveness. Method: The first implementation employed a quasiexperimental nonequivalent group design, whereas the second used a randomized experiment. A multivariate repeated-measures design compared intervention and control families from both implementations on parenting outcomes. Logistic regressions examined children's outcomes. Results: Compared to controls, intervention families significantly improved their family resources, parenting knowledge, practices, and maternal resilience. Intervention status significantly predicted children's immunization and early language. Conclusions: Parent mentoring anchored in multidisciplinary approach with empirically informed practices may be a desirable intervention addressing the multifaceted developmental needs of very young children. Limitations and implications for practice are addressed. (Contains 10 tables.)