Background: Regulatory problems (RPs; excessive crying, sleeping, or feeding difficulties) that co-occur (i.e., multiple) or are persistent have been associated with cognitive and behavioral problems in childhood. However, it remains unknown if multiple or persistent RPs are associated with cognitive and behavioral problems in adulthood. Methods: This large prospective longitudinal study (N = 759) was conducted in two cohorts in Germany (N = 342) and Finland (N = 417). RPs were assessed at 5, 20, and 56 months via the same standardized parental interviews and neurological examinations. In young adulthood, questionnaires were used to assess behavioral problems. Cognitive functioning was assessed with IQ tests. We examined the effects of multiple or persistent RPs on the outcomes via analysis of covariance tests and logistic regression controlled for the influence of cohort. Results: Of 163 participants with RPs, 89 had multiple and 77 had persistent RPs. Adults who had early multiple or persistent RPs (N = 151) reported more internalizing (p =.001), externalizing (p =.020), and total behavioral problems (p =.001), and, specifically, more depressive (p =.012), somatic (p =.005), avoidant personality (p <.001), and antisocial personality problems (p =.006) than those who never had RPs (N = 596). Participants with multiple or persistent RPs were more likely to receive any ADHD diagnoses (p =.017), particularly of hyperactive/impulsive subtype (p =.032). In contrast, there were no associations between multiple or persistent RPs and IQ scores in young adulthood. Conclusions: The results indicate long-lasting associations between multiple or persistent RPs and behavioral problems. Thus, screening for early RPs could help to identify children who are at risk for later behavioral problems.