Background: Longitudinal clinical experiences are a common component of undergraduate medical curricula, yet these programs have not been systematically characterized in US medical schools.Objective: Our study sought to identify and characterize longitudinal clinical programs (LCPs) in US medical schools and measure associations between programs’ structures and goals.Design: Using a mixed-methods approach, we conducted a secondary analysis of data from publicly available websites. We conducted a systematic keyword search of the websites of 137 LCME-accredited US medical schools to identify LCPs. We included programs with student–patient interactions of at least six months. We categorized programs using qualitative thematic analysis and compared associations between program structures and goals.Results: We identified 98 LCPs in 69 schools. Half (52.0%) of LCPs occurred during the core clinical year. Program structures included ‘clinic attachments’ (50.0%), ‘longitudinal integrated clerkships’ (26.5%), and ‘patient attachments’ (20.4%). We identified goals in 89 programs, including ‘exposing students to specific topics, patient demographics, or practice settings’ (78.7%); ‘clinical or professional skill development’ (65.2%); and ‘understanding the patient experience’ (19.1%). Patient attachments were associated with ‘exposure to specific patient demographics’ (P = .04) and ‘understanding the patient experience’ (P = .03). Pre-clinical programs were associated with clinical skills development (P = .01).Conclusions: Our study identifies the scope and nature of LCPs in US medical schools. Understanding connections between educational structures and goals may guide program design and research investigations of educational processes and outcomes.