Provided herein are methods for transducing a plurality of cells in a composition of cells, such as a population of lymphocytes, containing viral particles. In some aspects, provided methods and reagents for the transduction of cell populations involve binding of agents to a molecule on the surface of the cells. In some cases, the reagents are multimerization reagents and the one or more agents are multimerized by reversibly binding to the reagent. In some aspects, the multimerized agent can provide for transduction and/or expansion or proliferation or other stimulation of a population of cells, and then such agents can be removed by disruption of the reversible bond. Also provided are compositions, apparatus and methods of use thereof.