Context: Instrument-assisted soft tissue mobilization (IASTM), tissue flossing, and kinesiology taping are increasingly popular treatments among athletes for improving functional performance, despite limited evidence for their efficacy. Objective: Previous research regarding the efficacy of soft tissues and neuromuscular techniques on improving functional capacity of shoulder joints in athletes has yielded conflicting results. We examined the immediate and short-term effects of IASTM, flossing, and kinesiology taping on the functional capacities of amateur athletes’ shoulders. Design: Randomized controlled study. Setting: Clinical assessment laboratory. Participants: Eighty amateur overhead athletes (mean [SD]: age = 23.03 [1.89]; weight = 78.36 [5.32]; height = 1.77 [.11]). Interventions: We randomly assigned participants to 4 research sub-groups in which they received the following treatments on their dominant shoulders: IASTM (n = 20), flossing (n = 20), both IASTM and flossing (n = 20), and kinesiology tape (n = 20). Nondominant shoulders served as controls. Main Outcome Measure: We evaluated participants—before, immediately after, and 45 minutes after the therapeutic interventions—with the following tests: internal and external shoulder rotation range of motion, isokinetic strength and total work, the functional throwing performance index, and the one-arm seated shot put throw performance. Results: All therapeutic interventions significantly improved the strength and functional performance of the dominant shoulder in comparison with the control (P < .005) immediately after and 45 minutes after the treatment. The IASTM led to significantly greater improvement in shoulder internal rotation than kinesiology taping immediately after (P = .049) and 45 minutes after the treatment (P = .049). We observed no significant differences between the other treatment interventions (P > .05). Conclusion: Findings from the current study support the use of novel soft tissue and neuromuscular techniques for the immediate and short-term improvement of the shoulder functional capacities in amateur overhead athletes.