The Global Resilience Oral Workshops (GROW) Free and Strong programs take a strengths-based, positive youth development (PYD) approach to promoting thriving. Through both prevention (GROW Strong) and intervention (GROW Free) exercises, these programs aim to build character and emotional resilience while also lowering unhealthy alcohol use. To meaningfully assess the impact of the GROW programs on health and PYD, ecologically and psychometrically valid measures of character strengths were needed, with a focus on the strengths of hope, forgiveness, spirituality, prudence, and self-control (self-regulation) promoted by GROW. We tested a series of exploratory and confirmatory factor analyses of these five key constructs using two samples: a school-based youth sample enrolled in GROW Strong (n = 460; M[subscript age] = 15.04 years, SD[subscript age] = 1.21; 53.0% female); and a community-based adult sample enrolled in GROW Free (n = 457; M[subscript age] = 20.60 years, SD[subscript age] = 1.88; 49.7% female); both enrolled using a waitlist-control design. Measures demonstrated strong invariance across specific subgroups present in the data sets, with differences emerging across ages, urban/rural locations, and baseline study conditions. To meaningfully document PYD programs and character development in the majority world, measurement models must be theory-predicated, robust, and empirically validated for the specific context. The results provide evidence for such a measure that will be useful in future intervention studies promoting character strengths to address unhealthy alcohol use in Zambia.