The present invention relates generally to methods for stimulating, activating, and maintaining or increasing the polyclonality of expressed TCRs in a population of T cells. In the various embodiments, cells are stimulated with a surface, wherein the surface has attached thereto one or more agents that ligate a cell surface moiety of at least a portion of the T cells and stimulates at least a portion of the T cells, yielding enhanced proliferation, cell signal transduction, and / or cell surface moiety aggregation. In certain aspects methods for stimulating a population of cells such as T-cells, by cell surface moiety ligation are provided by contacting the population of cells with a surface, that has attached thereto one or more agents that ligate a cell surface moiety thereby inducing cell stimulation, cell surface moiety aggregation, and / or receptor signaling enhancement. Also provided are methods for producing T-cells for the use in diagnostics and the treatment of a variety of indications, including cancer, viral infection, and immune related disorders. Compositions of cells having increased polyclonality produced by these processes are further provided.