An extensive validation program was developed and implemented in support of computational mechanics of paratransit buses. The program is based on laboratory testing of coupons for material characterization (test level 1, TL 1) and connection tests (TL 2). Experimental data obtained from TL 1 tests were used for development of the finite element (F.E.) models of several structural components and connections of a paratransit bus selected for this study. The segments, critical for crashworthiness performance of the entire bus, included: a wall-to-floor, a wall-to-roof, and a sidewall panel of the bus. Resistance functions, relating a force applied vs. resulting displacement, were developed for each component. They were obtained from experimental tests (at TL 2) and from computational mechanics F.E. analyses. Comparison of the resistance functions and the failure mechanisms provided a good validation of the F.E. models of the major structural components which, in turn, were included in F.E. models of the entire paratransit bus. A model of the paratransit bus, with 600,000 finite elements, was developed for crashworthiness and safety assessment of the bus. AutoCAD files, material samples and components for testing were provided by the bus manufacturer to aid in the model development and validation processes. The Ls-Dyna nonlinear commercial code was used as major tools for numerical analyses. Two impact scenarios were considered: a rollover of a bus from 800 mm, and a 90⁰ side impact of the bus by a pickup truck at 48 km/h.