Initial success with B cell-targeted chimeric antigen receptor (CAR) T cells for the treatment of systemic lupus erythematosus and other rheumatic diseases has generated enthusiasm for the broad application of this technology outside of the field of oncology. Paediatric patients with severe rheumatic diseases require lifelong therapy with a substantial toxicity burden and a high cost of care. Paradigm-shifting treatments, including CAR T cells, are desperately needed. Although CAR T cell therapy shows promise for paediatric rheumatic diseases, there are unique aspects of care compared with adults, which require careful consideration and expertise. In response, we established the Integrated Multidisciplinary Paediatric Autoimmunity and Cell Therapy (IMPACT) working group, comprising international experts in the fields of paediatric rheumatology, oncology and cellular therapy, immunology and nephrology, to address the challenges of introducing cell therapies to patients with paediatric-onset autoimmune diseases. Given the possible benefits, we advocate for the study of CAR T cells in paediatric patients with rheumatic diseases who carry a lifelong risk of morbidity and mortality from chronic illness and medication toxicity. As this patient population is relatively small, consensus around definitions of success, robust study of predictors of response and uniform assessment and reporting of toxicities are critical to advancing the field.