During the development of T cells in the thymus, differentiating thymocytes move through specific thymic compartments and interact with the cortical and medullary microenvironments of the thymic lobules. This migration is primarily controlled by adhesion moleculesAdhesion molecules, such as extracellular matrixExtracellular matrix (ECM) ligands and receptors, and soluble factors like chemokinesChemokines that are important for thymocyte differentiation. The migration events driven by these molecules include the entry of lymphoid progenitors from the bone marrowBone marrow, movement within the thymus, and the exit of mature thymocytes. Notably, the migration of developing T cells can also impact the positive and negative selectionNegative selection processes, which are crucial for preventing the development of self-reactive T cells. This chapter will focus on the key molecules involved in thymocyte migration and how their expression patterns may affect T cell development and the formation of T cell repertoires.