The goal of ensuring that all children are "ready for school" has become a national priority. As a result, programs that support children's school readiness are becoming more and more important to policy-makers, funders, and parents. It is becoming very clear that efforts to improve school success cannot begin at kindergarten, nor focus exclusively on academics. Simply put, if children do not achieve early social and emotional milestones, they will not do well in the early school years, and are at higher risk for school problems and juvenile delinquency later in life. This fact sheet summarizes some of the most compelling infant and early childhood mental health (I/ECMH) research, and suggests some ways to improve the early social and emotional development of very young children. (Contains 38 endnotes.)