Purpose <p>Autonomous motivation and self-compassion may potentially influence outcomes in eating disorder treatment. Self-compassion may reduce&#xa0;criticism and shame, which have been implicated in the maintenance of anorexia nervosa. This study examined whether baseline autonomous motivation and self-compassion, and their interaction, were associated with changes in eating disorder symptoms in women with anorexia nervosa receiving inpatient treatment.</p> Methods <p>Participants were 56 women (<i>M</i> age = 23.8, range = 16–52&#xa0;years) diagnosed with anorexia nervosa and admitted to an inpatient eating disorder programme. Eating disorder symptoms (Eating Disorder Examination-Questionnaire; EDE-Q), autonomous motivation (Autonomous and Controlled Motivation for Treatment Questionnaire; ACMTQ), and self-compassion (Self-Compassion Scale-Short Form (SCS-SF) were measured at pre- and post-treatment.</p> Results <p>Latent change score models indicated that higher baseline autonomous motivation was associated with greater reductions in eating disorder symptoms across treatment. Baseline self-compassion and the interaction between autonomous motivation and self-compassion were not associated with changes in eating disorder symptoms. Post hoc Monte Carlo simulations indicated that the models were adequately powered to detect effects of the observed magnitude.</p> Conclusion <p>The findings are consistent with Self-Determination Theory in eating disorder populations and suggest that higher autonomous motivation is associated with greater reductions in eating disorder symptoms. Future research should examine whether interventions targeting autonomous motivation may be associated with improved treatment outcomes in women with anorexia nervosa.</p> Level of evidence <p>Level III: Evidence obtained from well-designed cohort or case–control analytic studies.</p>