This paper presents experimental and numerical results from an ongoing investigation to evaluate the performance of steel-timber composite floor systems. A composite floor system comprised of cross-laminated timber (CLT) made from Southern Yellow Pine species was fastened to a hot-rolled wide flange steel beam using self-tapping wood screws. Experimental evaluations included push out tests for mechanical fastener characterization and a beam test that was monotonically tested under a four-point bending setup. Beam test results were compared againsta steel-timber fiber model, existing equations adapted from steel-concrete composite design, and experimental steel-CLT load-slip response from the pushout testing. Near full-composite behavior was observed in the beam prior to connection slip but reduced to partial-composite behavior as screws began to deform. A substantial increase in strength and stiffness was observed for the composite beam from the non-composite (hybrid) case which was nearly equal to the level of composite action achieved during the test. Both the section fiber model and adapted steel-concrete composite design equations estimated the steel-CLT beam behavior with reasonable accuracy compared to the experimental test.