Addressing health inequalities requires detailed insights into local population behaviors beyond national averages. This study applies a multilevel regression with post-stratification (MRP) framework to assess chlamydia screening rates among young adults across England’s local authorities. By integrating individual-level demographic and behavioral data from the Natsal-3 survey with area-specific census and surveillance datasets, the model adjusts for socio-demographic heterogeneity and identifies regions performing above or below expectations. Bayesian hierarchical logistic regression was used to estimate expected screening rates, with significant variation attributed to factors such as age, gender, ethnicity, and student status. The analysis reveals that while demographic composition explains much of the variation, notable outliers suggest opportunities for targeted intervention.