Rationale-Aims and Objective: The validation study of the Patient Assessment of Chronic Illness Care (PACIC) questionnaire suggested a 5-factor structure determined a priori, but subsequent analyses have questioned the validity of the original factor structure. This study analyzed the factor structure of the PACIC using a large and diverse patient sample, and evaluated the identified factors through the lens of recent transformational initiatives in primary care.Methods-Convenience samples of adults completed surveys in waiting rooms during clinic visits. Primary care patients with 1 or more chronic illnesses with complete PACIC responses at baseline from 39 clinics (n=1,567) and at follow-up from 36 clinics (n=1,536) participated. Exploratory and confirmatory factor analyses were conducted on baseline and follow-up patient questionnaire data from a cluster randomized controlled trial. Identified factors were evaluated in terms of item loadings, content, reliability, and the extent to which items reflected advances in the delivery of chronic illness care.Results-Analyses supported the use of the PACIC summary score. Although a 5-factor model was retained, factor loadings were different from the original PACIC validation study. All factors had sufficient reliability, but findings suggested potential revisions to enhance the factor structure.Conclusions-It may be time to revise the PACIC to enhance the stability of the subscales (factors) and better reflect recent transformations in the delivery of chronic illness care.