Media messages can motivate parent support for children's physical activity (PA). Unfortunately, many PA messages targeting parents are not necessarily inclusive of parents of children with disabilities (CWD) and the effects of messages on the support behaviour of parents of CWD is unknown. Guided by the Theory of Planned Behaviour and Multi-Process Action Control model, the relative effects of PA messages were examined among parents of CWD. Parents (N=135) were randomized to view one of the following messages: a) targeted (i.e., CWD in sport/competitive context), b) generic (i.e., no children included), c) non-inclusive (i.e., able-bodied children only), and d) inclusive (i.e., able-bodied and CWD). Parent PA support and various psychosocial antecedents (e.g., attitudes, subjective norms, PBC, intention, behavioural regulation) were assessed before, immediately post- and two-weeks post message viewing. A multivariate main effect for time was observed. Post-hoc analyses identified baseline parent support as a moderator of the effects of message viewing: parent support increased post-viewing among parents with low baseline support, and decreased among parents with high baseline support. Subjective norms also increased among parents with low baseline parent support. Planning increased among parents with low baseline parent support, and decreased among parents with high baseline parent support. The results of this study can inform the development of optimally effective messages to motivate parent PA support among parents of CWD.