This paper presents the design method for slim-floor construction that comprises a steel beam and a concrete or composite floor slab in which the beam is integrated within the depth of the slab. The slabs are either supported on a plate attached to the bottom flange or the bottom flange of the beam itself. The main design parameters and load transfer mechanisms are discussed. Plastic analysis has been adopted for the design of the bending capacity at the ultimate load condition and the design procedures described are in accordance with the principles given in Eurocode 4. Attention is paid to the type of shear connection between steel and concrete.