Inequitable gender norms and beliefs contribute to increased sexual risk behavior, and, among adolescent girls and young women (AGYW), risk of HIV acquisition. We investigated the longitudinal measurement properties of the Gender Equitable Men’s Scale (GEMS) when applied to a cohort of AGYW in rural South Africa (2011–2015). We used item response theory [Person-Item maps, Differential Item Functioning (DIF)] and measurement invariance confirmatory factor analysis models to assess the validity and reliability of the GEMS instrument. Item difficulty and endorsement of gender equitable beliefs both shifted over time. DIF analysis identified item bias for over half of the items; influenced by age, pregnancy, sexual debut, and intimate partner violence. Measurement invariance models revealed strong longitudinal invariance properties. GEMS is a reliable longitudinal measurement of gender equitable beliefs, with notable bias for specific items when administered to subgroups. Additional items specific to the adolescent experience are warranted for a more stable assessment of gender equitable beliefs in a population facing shifting norms as they mature.

不公平的性别规范和信仰导致性风险行为增加，并且在青春期女孩和年轻女性 (AGYW) 中增加了感染 HIV 的风险。我们研究了将性别平等男性量表 (GEMS) 应用于南非农村地区 AGYW 队列（2011-2015 年）时的纵向测量特性。我们使用项目响应理论 [Person-Item maps，Differential Item Functioning (DIF)] 和测量不变性验证因子分析模型来评估 GEMS 工具的有效性和可靠性。项目难度和对性别平等信念的认可都随着时间而变化。DIF 分析确定了超过一半项目的项目偏差；受年龄、怀孕、首次性行为和亲密伴侣暴力的影响。测量不变性模型揭示了强大的纵向不变性。GEMS 是对性别平等信念的可靠纵向测量，在对亚组进行管理时对特定项目有显着偏差。需要针对青少年经历的其他项目进行更稳定的评估，以便更稳定地评估随着他们成熟而面临改变的人群中的性别平等信念。