Background: Multiproblem families are multi-users of psychosocial and health care services, but little is known about factors associated with their care utilization in the general population. The aim of this study was to assess which factors were associated with the overall and psychosocial care use of two members—i.e., child and parent—of each multiproblem family. Methods: During well-child visits or psychosocial care, we identified 354 children and their parents who had problems in several life domains (response 69.1%). We used multivariate stepwise backward logistic regression analyses to identify the factors related to their use of overall and psychosocial care. Results: A child's overall care use was associated with greater social support from family and friends (odds ratio, OR, 95% confidence interval, CI; OR = 1.05, CI = 1.01–1.08) compared to less perceived social support; and with more psychosocial problems in the child (OR = 1.84, CI = 1.04–3.24). Child's psychosocial care use was more likely among older children (OR = 1.94, CI = 1.20–3.15); greater social support by family and friend (OR = 1.03, CI = 1.00–1.06); more psychosocial problems (OR = 1.75, CI = 1.04–2.97); and when there were more parenting concerns (OR = 1.19, CI = 1.06–1.33). Parental overall and psychosocial care use was more likely when the family experienced a higher number of life events (OR = 1.27, CI = 1.17–1.38, and OR = 1.39, CI = 1.25–1.55). Conclusions: Care use in multiproblem families is related to family factors as well as psychosocial problems. It may be possible to use these family risk factors to identify such families early, whose intensive care use is possibly explained by the relationship with inadequate use of social support.