Autistic adults self-harm more often than non-autistic adults, but there are no tools to assess patterns of self-harm in autistic people. This study aimed to (1) review the accessibility of a novel visual task – the Card Sort Task for Self-Harm (CaTS) – to explore self-harm with autistic adults and (2) to pilot the CaTS to identify proximal and distal contributing factors leading to self-harm and experiences following self-harm. First, autistic adults (n = 5) with lived experience of self-harm reviewed the CaTS for clarity and accessibility. Second, we undertook a pilot administration of the CaTS and used sequence analysis to explore significant transitions between factors before and after self-harm. Participants (n = 29, autistic or possibly autistic, female = 82%, mean age = 41.62) selected, on average, 42 cards to describe self-harm. Most frequently selected cards described agitation (n = 25), mental pain (n = 22) and depression (n = 22), while most infrequently collected cards included being in a gang and talking to a teacher (n = 0). Agitation and acting on impulse preceded self-harm. Feeling better, worse, exhausted and hopeless followed self-harm. Improving emotion regulation and meeting autistic communication needs could reduce the transition to self-harm. The CaTS offers a systematic approach to explore self-harm in autistic adults.