Policies and proposals to promote marriage have been in the public eye for several years, driven by concern over the large percentages of U.S. children growing up with only one parent. This brief reviews the research evidence on the effects of family structure on children, as well as key trends in family structure over the last few decades. The brief notes an extensive body of research indicating that children do best when they grow up with both biological parents in a low-conflict marriage. At the same time, research on how to promote strong, low-conflict marriages is thin at best. The brief also discusses promising strategies for reducing births outside of marriage and promoting strong, stable marriages. (Contains 46 endnotes.) (EV)