Despite recognition that youth civic engagement is multidimensional, different modeling approaches are rarely compared or tested for measurement invariance. Using a diverse sample of 2,467 elementary, middle, and high school-aged youth, we measured eight dimensions of civic engagement: social responsibility values, informal helping, political beliefs, civic skills, environmental behavior, volunteering, voting intentions, and news consumption. We compared correlated unidimensional factors, higher-order factor, and bifactor models and tested for measurement invariance and latent mean differences by age. The correlated unidimensional factors model best fit the data, yet higher-order and bifactor models fit adequately. Metric and scalar invariance was found across models. Latent means varied depending on the dimension of civic engagement and the multidimensional model examined. Findings favored the correlated unidimensional factors model; implications of each model are discussed. This study informs future research on youth civic engagement and has broad relevance for any developmental scientist studying a multidimensional construct.