The present work describes the experimental tests on steel and lightweight concrete composite beams performed at University of Minho. The study involves tests on simply supported composite beams of 4.5 m span, with the same geometrical disposition, supports and materials. The geometrical configuration for the cross section and supports is identical for every beam, varying the shear connectors’ distribution and the loading conditions. Headed studs are used to provide the connection between the steel profile and the concrete slab. The parameters in study are the stud disposition and the load distribution. The main objective is to describe the composite beams behaviour, focused on its connection, and to analyse the contribution of the different components to the beams load and deformation capacity. All the tests explored the beams maximum load and deformation capacity and different types of failure were observed.