The present study examined the long-term treatment outcomes of the family-centered program Intensive Family Treatment (IFT) for families with multiple problems. We also tested the hypothesis that parental empowerment at the end of IFT constitutes a buffer between the negative influences of parental stress on their children’s behavioral problems afterwards. We included 275 families with multiple problems. Information about parental empowerment and child behavioral problems was gathered at the start and end of IFT and at follow-up, on average 2.8 years (SD = 1.6) later. At follow-up, information was also collected about parental stress and professional support. Data were analyzed through latent regression analyses. Significant improvements in child behavioral problems (effect size 0.60) and parental empowerment (effect size 0.53) were observed during treatment. Improvements were sustainable for child behavioral problems after IFT. Nevertheless, child behavioral problems remained severe on average and might be a stressor for parents. Together with other environmental stressors after IFT, these problems can increase parental stress and subsequently increase child behavioral problems. However, taking into account that professional support after IFT often still is needed, the findings of our study showed that parental empowerment at the end of IFT constitutes a buffer; parental stress had a less negative influence on child behavioral problems at follow-up when parents had a higher level of parental empowerment at the end of IFT. This study stresses the importance of empowering parents during family treatment to successfully cope with environmental stressors after treatment, including the problematic behavior of the child.