Persuasive messages have demonstrated value in motivating youth to engage in physical activity (PA). However, there is no known research examining the use of messages to motivate youth with disabilities (YWD), or how to create effective messages for them. Guided by the Social Issue Advertising Believability Model (SIABM), the purpose of the study was to i) examine the effectiveness of PA messages on YWD's attitudes toward PA and intentions to participate in PA, and ii) consider factors related to message effectiveness. YWD (N=60) were randomized to view one of three PA messages: a) neutral, b) non-inclusive, and c) targeted. Attitudes and intentions to participate in PA were assessed at baseline and immediately following viewing one of the three messages. Participants also evaluated the messages in terms of relevance, believability, attention, and attitudes. Repeated measures ANOVA indicated that attitudes and intentions toward PA did not change significantly following message viewing. YWD perceived the targeted message to be preferred and most believable. Attention to the message was the only significant predictor of intention to participate in PA post-viewing (p=.001). High sample baseline attitudes, intentions and PA likely contributed to the null effects of messages. Targeted messages may be perceived as more believable than non-targeted messages and thus may be of value in PA messaging campaigns for YWD. The relationship between message attention and PA intentions warrants further exploration. Research among a sample with lower baseline attitudes and intentions would be valuable in further informing the development of effective PA messages for YWD.