Research literature review of evidence of effectiveness of home visiting program models that serve families with pregnant women and children from birth to age 5. This report describes key lessons learned from the first year of the review from the current state of evidence on effectiveness of early childhood home visiting, gaps in research literature, and suggestions for strengthening future research, issues related to assessing replication of findings, measurement issues, challenges related to determining whether the effects are meaningful, interpretation of subgroup findings and implementation issues.