Previous research has neither fully examined family structure across the life course nor considered increasing variation in family types. Using data from the National Longitudinal Study of Adolescent Health (N = 11,318), I examine the influence of longitudinal measures across childhood of family structure duration and the number and timing of parent transitions (entrances and exits) on indicators of grade point average (GPA), college expectations, and suspension or expulsion in adolescence. I also examine whether parent gender moderates these effects. Results show that mother transitions during early childhood affect all outcomes, whereas time in mother-absent families influences GPA and school discipline. I find evidence for parent gender differences in transition effects; mother transitions, especially early ones, have more severe consequences than father transitions.