Many existing reinforced concrete bridges in The Netherlands are suspected of having insufficient shear strength, hence a methodical approach is necessary to assess them. The aim of this paper is to provide a structured approach for assessment of the reinforced concrete slab bridges, which make up a considerable proportion of the Dutch bridge stock. The proposed method uses the levels of approximation introduced in the fib Model Code for Concrete Structures 2010. The recommendations at all levels are linked to experimental research. The different levels include spreadsheet-based calculations (the “Quick Scan”), linear finite element models, nonlinear finite element models, the analysis of a structure with cracked concrete, and, for exceptional cases, proof loading of the structure. The result of this approach is a structured method of levels of assessment that can be used when many bridges need to be assessed. For most bridges, assessment at the lowest level will prove sufficient. For a limited number of cases, higher levels of assessment will offer options and guidelines for a more in-depth study of the structure being assessed.