Pediatric functional abdominal pain disorders (FAPDs) are associated with increased health care utilization, school absences, and poor quality of life (QoL). Cost-effective and accessible interventions are needed. This multisite study tested the effects of a 3-session cognitive behavioral intervention delivered to parents, in-person or remotely, on the primary outcome of pain severity and secondary outcomes (process measures) of parental solicitousness, pain beliefs, catastrophizing, and child-reported coping. Additional outcomes hypothesized a priori and assessed included functional disability, QoL, pain behavior, school absences, health care utilization, and gastrointestinal symptoms. The study was prospective and longitudinal (baseline and 3 and 6 months' follow-up) with 3 randomized conditions: social learning and cognitive behavioral therapy in-person (SLCBT) or by phone (SLCBT-R) and education and support condition by phone (ES-R). Participants were children aged 7 to 12 years with FAPD and their parents (N = 316 dyads). Although no significant treatment effect for pain severity was found, the SLCBT groups showed significantly greater improvements compared with controls on process measures of parental solicitousness, pain beliefs, and catastrophizing, and additional outcomes of parent-reported functional disability, pain behaviors, child health care visits for abdominal pain, and (remote condition only) QoL and missed school days. No effects were found for parent and child-reported gastrointestinal symptoms, or child-reported QoL or coping. These findings suggest that for children with FAPD, a brief phone SLCBT for parents can be similarly effective as in-person SLCBT in changing parent responses and improving outcomes, if not reported pain and symptom report, compared with a control condition.