We reviewed the literature on the assessment of acceptability of HIV prevention and treatment interventions and service delivery strategies. Following PRISMA guidelines, we screened 601 studies published from 2015 to 2020 and included 217 in our review. Of 384 excluded studies, 21% were excluded because they relied on retention as the sole acceptability indicator. Of 217 included studies, only 16% were rated at our highest tier of methodological rigor. Operational definitions of acceptability varied widely and failed to comprehensively represent the suggested constructs in current acceptability frameworks. Overall, 25 studies used formal quantitative assessments (including four adapted measures used in prior studies) and six incorporated frameworks of acceptability. Findings suggest acceptability assessment in recent HIV intervention and service delivery research lacks harmonization and rigor. We offer guidelines for best practices and future research, which are timely and critical in this era of informed choice and novel options for HIV prevention and treatment.