There is a large body of research that shows children from non-intact homes show higher rates of juvenile delinquency than children from intact homes, partially due to weaker parental control and supervision in non-intact homes. What has not been adequately addressed in the research is the influence of changes in family structure among individual adolescents over time on delinquent offending. Using the first and third waves of the National Youth Study, we assess the effect of family structure changes on changes in delinquent offending between waves through the intermediate process of changes in family time and parental attachment. Although prior research has documented adolescents in broken homes are more delinquent than youth in intact homes, the process of family dissolution is not associated with concurrent increases in offending. In contrast, family formation through marriage or cohabitation is associated with simultaneous increases in offending. Changes in family time and parental attachment account for a portion of the family formation effect on delinquency, and prior parental attachment and juvenile offending significantly condition the effect of family formation on offending.