OBJECTIVE. It has been suggested that the addition of behavioral interventions to laxative therapy improves continence in children with functional fecal incontinence associated with constipation. Our aim was to evaluate the clinical effectiveness of behavioral therapy with laxatives compared with conventional treatment in treating functional constipation in childhood. PATIENTS AND METHODS. In this randomized, controlled trial conducted in a tertiary hospital in the Netherlands, 134 children aged 4 to 18 years with functional constipation were randomly assigned to 22 weeks (12 visits) of either behavioral therapy or conventional treatment. Primary outcomes were defecation frequency, fecal incontinence frequency, and success rate. Success was defined as defecation frequency of ≥3 times per week and fecal incontinence frequency of ≤1 times per 2 weeks irrespective of laxative use. Secondary outcomes were stool-withholding behavior and behavior problems. Outcomes were evaluated at the end of treatment and at 6-months follow-up. All of the analyses were done by intention to treat. RESULTS. Defecation frequency was significantly higher for conventional treatment. Fecal incontinence frequency showed no difference between treatments. After 22 weeks, success rates did not differ between conventional treatment and behavioral therapy (respectively, 62.3% and 51.5%), nor did it differ at 6 months of follow-up (respectively, 57.3% and 42.3%). The proportion of children withholding stools was not different between interventions. At follow-up, the proportion of children with behavior problems was significantly smaller for behavioral therapy (11.7% vs 29.2%). CONCLUSION. Behavioral therapy with laxatives has no advantage over conventional treatment in treating childhood constipation. However, when behavior problems are present, behavioral therapy or referral to mental health services should be considered. Copyright © 2008 by the American Academy of Pediatrics.