This fact sheet explores unique stepfamily characteristics and stepfamily dynamics. Data is shared on the number of stepfamilies, different types of stepfamilies, and nonresidential and cohabiting stepfamilies. It is estimated that between 10 and 20% of U.S. children reside in stepfamilies, and data is reported that indicates between 1997 and 2002, the percentage of stepfamilies did not increase significantly for any racial group except for Hispanics. Compared to children living with both biological parents, the fact sheet states children in stepfamilies tend to have more struggles with behavior problems, emotional well-being, and academic achievement. In addition, adolescent stepchildren are more frequently engaged in drug and alcohol use and sexual activity. The limitations of current datasets and the need for additional research are emphasized. 15 references.