The regulation of naive T cell development into different effector cell subsets is mediated by a complex interplay between the cytokine microenvironment, receptor ligand interactions on the T cell and the antigen presenting cell, and the potency of T cell receptor (TCR) signaling. In this review we will focus on how alterations in the strength of TCR ligation initiate different signal transduction patterns which regulate the developmental fate of naive T cells. We propose a model in which specific signals are required to initiate Th2 differentiation, but that this pathway can be inhibited following a strong TCR stimulus.