Background: Applied behaviour analysis (ABA) therapists typically work one-to-one with children with autism for extended periods of time, which often leads to high levels of job-related stress, lower levels of job satisfaction, increased frequency of occupational "burnout" and higher than average job turnover (Journal of Autism Development, 39, 2009 and 42). This is particularly unfortunate, in that these vulnerable clients need stability and consistency in care, both of which are empirically related to clinical outcomes (Journal of Autism Development, 39, 2009 and 42). It is reasonable to assume that some individuals, by virtue of their personal characteristics, are better suited to this type of work than are others. Method: The purpose of the this study was to investigate associations between personality traits, using the five-factor model of personality, and key job-related variables, including burnout and job satisfaction, in a sample of therapists ("n" = 113) who work one-to-one with individuals diagnosed with autism. Results: Significant correlations were found between Neuroticism and all three subscales of burnout (Exhaustion, Cynicism and Professional Efficacy). Extraversion and Conscientiousness were significantly negatively correlated with Cynicism and positively correlated with Professional Efficacy. Agreeableness was positively associated with Professional Efficacy. Job satisfaction was correlated positively with Extraversion and negatively with Neuroticism. Level of perceived personal and professional support partially mediated the effect of personality traits on job satisfaction. Conclusions: These results may help to identify job applicants who are dispositionally less suited to this type of work, as well as currently employed therapists who are in need of support or intervention. (Contains 4 tables.)