ObjectiveEstablish between-day test-retest reliability metrics for 2-dimensional frontal plane projection angles (FPPAs) during the lateral step-down (LSD), single-limb squat (SLS), single-limb landing (SLL), and drop vertical jump (DVJ). DesignTest-retest reliability study. SettingUniversity laboratory. Participants20 healthy adults (12 female, age = 23.60 ± 1.93 years old, body mass index = 24.26 ± 2.54 kg/m2) were tested on 2 separate occasions 7–14 days apart. Main outcome measuresIntraclass correlation coefficients (ICC), standard errors of the measurement (SEM), and minimal detectable change (MDC) values across the LSD, SLS, SLL, and DVJ for the following body region variables: trunk, trunk on pelvis, pelvis, hip, thigh to vertical, knee, and shank to vertical. ResultsThere was moderate-to-substantial between-day test-retest reliability for nearly all body regions across all tasks (ICC = 0.65–0.96). SEM values varied across body regions and tasks (0.9–3.5°). MDCs were variable (2.3–9.8°). Of the body regions, MDCs were largest for the knee and hip. By task, MDCs were lowest for the LSD. ConclusionsThis study identified between-day test-retest reliability metrics for 2-dimensional FPPAs across a variety of body regions during commonly assessed clinical tasks. These data allow clinicians and researchers to more confidently assess true change between assessments or over time.