The importance of building capacity in community interventions is well recognized. There is general agreement about the determinants of capacity and a range of existing capacity frameworks, however there is limited evidence or consistency in practice around assessing capacity in community interventions. The aim of this review was to describe how capacity is assessed in community interventions. A systematic review of the literature across four databases (MEDLINE, CINAHL, PsycINFO and Sociological Abstracts) was performed. Studies in English from 2000 to 2017, that explicitly described how capacity building processes were assessed in community interventions in healthy populations, were included. All types of empirical study designs were eligible. From 2596 records, after exclusion criteria were applied, 19 studies were included describing 12 different capacity assessment frameworks or tools. Seventeen studies assessed capacity processes by measuring individual capacity domains in community interventions. The most common capacity domains used to assess capacity were leadership, resources, partnerships and intelligence. The majority (n = 15) of studies used qualitative or mixed methods designs to measure capacity. Nine studies assessed capacity prospectively over time; three before/after and six multiple times during the intervention. Five studies assessed capacity retrospectively. The findings suggest that capacity assessment may need to remain context specific and flexible in order to capture the ever-changing nature of capacity building over time. Future research should explore the utility of theoretical adaptive capacity assessment guidelines that direct researchers and practitioners when describing capacity assessment in community interventions.