We examined the link between trajectories of television contact time at ages 1-5 and externalizing problems at age 5, using data from a Japanese longitudinal study of media use and child development (N = 1,189). Despite the American Academy of Pediatrics recommendation for no television contact before age 2, growth mixture modeling identified 3 trajectory classes, comprising heavy-start contact (8%, mean contact time at age 0 = 331.44 min/day), characterized by remarkably long television contact time in infancy and maintenance of longer contact, while mild contact (51%, 147.57 min/day) and moderate contact (41%, 236.64 min/day) had relatively shorter contact in infancy and moderate declines in later years. The findings suggest that both infant temperamental difficulties and family characteristics predicted trajectory classification of television contact time. Scores for attention problems and conduct problems at age 5 did not significantly differ among trajectory groups, nor did regression coefficients.