Efficacy, cohesion, and sport performance have been shown to vary longitudinally (Carron et al., 2002; Shea & Howell, 2000). Tripartite efficacy is a specific area concerning efficacy beliefs within dyads that has recently grown in popularity (Jackson et al., 2013); yet no longitudinal research of intra-dyad beliefs exists. This case study examined longitudinal variations of tripartite efficacy beliefs, cohesion, and individual performances of six basketball players on a high school team over seven data collection points during a competitive season. The results indicated similar variations between participants' tripartite efficacy components and individual performance, and different variations between self-efficacy and cohesion beliefs. / Access to thesis permanently restricted to Ball State community only. / School of Physical Education, Sport, and Exercise Science