<p>Restrictive and repetitive behaviours are part of autistic identity. However, in clinical decision making, there are too few representative examples, qualitative descriptors, and personal meanings of rituals and routines in particular. This systematic review sought descriptions of repetitive behaviours from autistic young people, their families, and professionals. Constructivist grounded theory analysis illustrated the unsuitability of diagnostic criteria alone in defining autistic behaviours. Repetitive behaviours were meaningful when described by autistic people. They provided coping strategies and a window of time when a person felt at ease in their world, with fewer cognitive, social, and sensory demands. The visibility, excess, and inflexibility of repetitive behaviours demonstrated an autistic person’s responsiveness to demanding contexts. A definition of autistic repetitive behaviours is presented.</p>