Research regarding attitudes toward individuals with Autism spectrum disorder (ASD), particularly the attitudes of adults and adolescents is notably lacking within the research literature. Previous research would suggest that adults with ASD have very poor outcomes in later life, particularly in areas of employment and relationships. Research surrounding attitudes suggests that attitudes have an impact on behaviour, highlighting the need to establish the attitudes that society currently hold toward ASD. However, there are inconsistencies within the literature regarding implicit and explicit attitudes toward ASD. Therefore, Study 1 aimed to examine adults’ implicit and explicit attitudes toward ASD and sought to investigate the impact of gender on participants’ attitudes. Participants (N = 41) completed several explicit measures; The Openness to Autism Scale (OAS), The Attitudes to autism scale (AAS) and The Knowledge of Autism Questionnaire (KAQ), participants also completed an implicit measure, the implicit relational assessment procedure (IRAP). Results revealed that adults had significantly positive attitudes toward ASD. It was also revealed that attitudes did not significantly differ across gender nor were there significant differences across explicit and implicit measures. While the results of Study 1 were notably positive previous research suggests that as a result of their advancing development adolescents may be better able to determine differences between themselves and their peers with ASD and therefore may be less inclined to initiate social interactions with these peers. Study 2 therefore sought to determine adolescents’ attitudes toward their peers with ASD and investigate the effectiveness of an educational intervention to positively alter attitudes. Study 2 also employed a gender analysis. Participants (N = 31) completed the IRPA, the OAS and the AAS pre-and post the educational intervention. As a result of high attrition rates within the participant sample (N = 15), resulting from failure to reach pre-intervention IRAP criteria, an intention to treat (ITT) analysis was employed. Overall, the intervention had no significant impact on students’ attitudes regarding ASD. However, students reported significantly positive attitudes toward ASD prior to and following the implementation of the intervention. As with Study 1, no differences were found across gender within students’ implicit attitudes. Finally, the use of ITT analysis was an exploratory but beneficial element to the current study and a number of differences were reported across the methods of ITT. Future IRAP studies should continue to examine alternative methods of data analysis for instances of high attrition rates.