An inverse Finite Element Method (iFEM) is presented for beam and frame structures. The method is aimed at reconstructing the complete displacement field starting from in situ measurements of surface strains. A laboratory experiment is conducted on a simple cantilever beam subjected to various static loadings. Experimentally measured strains are used within a single-element iFEM model to assess the efficiency and predictive capability of the approach with respect to uncertainties and measurement errors that unavoidably affect real structures.