Parental support is an important contributor to physical activity (PA) among children and youth with disabilities (CYD). Although many parents of CYD are motivated to support PA, CYD are less physically active than typically developing children. The multi-process action control (M-PAC) framework has been applied to understand parental support for child PA, which highlights behavioral strategies such as action planning (AP) as critical for translating intentions into behavior. Parents may struggle to create and carryout AP without support. There is no known research examining telephone-assisted AP as a tool to promote AP and subsequent parental PA support among CYD. Purpose: To evaluate a 4-week telephone-assisted AP intervention for promoting parental support for PA among CYD. Method: Parents of CYD (Child Mage= 12.53 ± 5.53; 75% male; 38.6% developmental disability) completed a baseline questionnaire guided by the M-PAC framework and were subsequently randomized to a bi-weekly telephone-assisted AP intervention (n= 28) or control group (i.e., access to AP tools but no telephone assistance; n= 29). Results: Compared to the control group, parents who received the telephone-assisted AP intervention were 80% more likely to AP. Repeated measures ANCOVAs showed a significant time x condition interaction for behavioural strategies (i.e., planning, monitoring) (F(1,35)= 5.39, p= .026). Conclusion: Compared to the control condition, parents in the AP telephone-assisted intervention increased behavioural strategies to support their child's PA participation. These findings suggest potential for AP support as a tool to enhance AP and parent support for PA among CYD.