Voluntary parenting programs vary in format, the specificity of their goals, their target populations, and in the extent to which they have demonstrated effectiveness for improving parenting behavior, skills, and knowledge. Home visiting programs, which provide support and education to parents in the home through a trained professional (e.g., nurse or social worker) or paraprofessional, have a growing evidence base and have expanded rapidly over the last decade as a state-based investment in supporting parents and children. Although research has examined the impact of home visiting on a range of outcomes, the scope of this review is intentionally limited to parenting outcomes, the policy goal for which the most evidence on home visiting exists. States differ in how they fund home visiting (i.e., state and/or federal sources), their level of investment, and how they define the scope and goals of home visiting programs. (author abstract)