This study examines the relation between family instability and child maladjustment over a 6-year period in 369 children from four communities. Measures were collected annually from kindergarten through fifth grade. In associative growth curve models, family instability trajectories predicted children's externalizing and internalizing behavior trajectories during this time period. High levels of family instability also incrementally predicted the likelihood of meeting criteria for a DSM IV diagnosis during elementary school, above and beyond prediction from earlier measures of maladjustment. However, the timing of family instability had a different effect on externalizing versus internalizing disorders. In general, stronger relations were found between family instability and externalizing behaviors relative to internalizing behaviors, although children with comorbid disorders experienced the highest levels of family instability.