Objectives: Mixed methods were used to evaluate a group self-management education intervention to address type 1 diabetes (T1D)-specific barriers to physical activity (PA). We evaluated the acceptability of study resources and procedures. Methods: Consenting participants from a quantitative evaluation (n=70) were invited to participate in 1 of 5 focus groups. Interviews explored the acceptability of procedures across the randomized controlled trial schedule, acceptability of the intervention/control workshops and resources and the perceived effectiveness of the intervention/control on participant outcomes. The use and helpfulness of intervention take-home resources, Facebook data and fidelity coding were also examined to inform other aspects of intervention acceptability. Results: Twenty-one focus group participants from control or intervention arms participated in 1 of the 5 focus groups. Participants were 46±10 years of age; about half were female and had been living with T1D for 23±16 years. Study procedures were widely accepted; however, randomization and some aspects of the questionnaire were of concern to a small number of participants. Group education was acceptable and preferred, but participants expressed ambivalence toward the private Facebook group. Control participants indicated that basic information on PA guidelines and hypoglycemia risk are not currently being provided in standard care. Fidelity assessment confirmed the intervention was delivered consistently and was facilitated using behaviours and communication skills based on Social Cognitive Theory. Conclusions: Future definitive evaluation of this promising intervention should utilize a blinded randomized controlled trial study design. Alterations to the control workshop are required to better reflect standard care in Australia. Our qualitative findings suggest that group education can be an acceptable and preferred method of education in T1D management for PA. © 2021 Canadian Diabetes Association