Aim: To develop the Primary care fUnctions of Family physicians in Childhood Asthma (PUFFinCA) scale for evaluating the cardinal process functions of primary care services (accessibility, comprehensiveness, continuity and coordination) provided by family physicians (FPs) in the management of childhood asthma. Background: In the literature on the functions of primary care, there is no assessment tool focusing on children with asthma. Primary care assessment scales adapted to various languages are not suitable to adequately address the needs of special patient groups, such as children with asthma. Methods: In this methodological study, the instrument development process was completed in four stages: establishing the pool of items, evaluating the content validity, applying the scale and statistical analysis. The scale was applied to 320 children who had asthma and received care in the clinic of the Department of Pediatrics, Division of Allergy and Pulmonology at Ege University School of Medicine, Turkey. The Cronbach's a and Spearman-Brown coefficient were calculated to determine the reliability of the scale. Principal component analysis was used to determine the construct validity of the scale. Findings: The PUFFinCA scale was found to have four-factor structure and 25 items. Cronbach's a coefficient was 0.93. It has been determined that the reliability was excellent and the item-total correlation coefficients were >0.30 each. The factors were titled FP's 'functions of accessibility, first contact and continuity', 'functions of coordination and comprehensiveness of health services related to asthma management', 'provision of preventive care related to asthma' and 'provision of services for paid vaccinations'.