The presence and quality of friendships are posited to have developmental significance, yet little is known about the extent to which children without friends versus low-quality friendships compare on socioemotional adjustment. The current study utilized data from a subsample of 567 children (289 boys) participating in the NICHD Study of Early Child Care and Youth Development. Based on maternal reports at kindergarten, four friendship groups were formed: no friends, low quality, average quality, and high quality, and these groups were used to predict teacher-reported behaviour problems and social skills concurrently (in kindergarten) and longitudinally (in first and third grade). Concurrently, low-quality friendships were associated with greater externalizing behaviour, whereas high-quality friendships were associated with greater social skills. Longitudinally, having no friends in kindergarten was associated with higher levels of externalizing behaviour for boys, but lower levels for girls. Children without friends also showed more internalizing problems at first grade. Lastly, having a high-quality friendship in kindergarten was associated with greater social skills in first and third grades, but only for boys. Results underscore high-quality friendship as a context for the development of social skills and indicate different trajectories of problem behaviour for kindergarten children with no friends versus low-quality friendships. Copyright © 2010 John Wiley & Sons, Ltd.