To better understand the behavior of composite beams in buildings, push-out tests were conducted to study the behavior of welded shear studs. Forty-eight solid slab push-out tests were conducted to study how stud tensile strength and concrete properties affect the strength of shear connections. It is shown that raising the tensile strength of a shear connector actually has an adverse effect on the connector's performance and strength. It is also shown that the upper limit for shear strength used in the current AISC specification (Load 1993) is unconservative and a lower upper limit is proposed. Eighty-seven pushout tests utilizing steel deck were also conducted. It is shown how the placement, height, and arrangement of shear studs, as well as the height and gage of steel deck affects the strength of shear connections when stiffened steel deck is used. It is shown that the current AISC specification is unconservative and does not account for the many failure mechanisms associated with connections using steel deck. It is shown how tension within the stud shank, friction at the slab/beam interface, and steel deck strength affect the strength of shear connections. / Master of Science