Adolescents on the autism spectrum often have difficulties with the transition from high school to post-school activities. Despite this, little is known about the transition planning processes for this group. This study explored predisposing, reinforcing and enabling factors related to the transition planning processes for adolescents on the autism spectrum in Australia. The PRECEDE model guided a needs assessment, in which descriptive data about transition planning processes were collected via an online questionnaire from adolescents on the autism spectrum, their parents and professionals (N = 162). Predisposing factors included: an individualised and strengths-focused approach, and adolescent motivation, anxiety and insight. Reinforcing factors included: support and guidance, skill development and real-life experiences. Enabling factors were: having a clear plan with a coordinated approach, scheduled meetings and clear formal documentation. Whilst some factors aligned with recommendations for transition planning for adolescents with disabilities in general, there were some autism-specific factors. For example: anxiety, motivation and insight were important predisposing factors, and providing choice and flexibility was an enabling factor.