© 2013 Springer Science+Business Media New York. All rights are reserved. Lymphatic vessels are intimately involved in the maintenance of tissue homeostasis, immune cell trafficking, and transport of dietary lipids. During embryonic development, growth of new lymphatic vessels or lymphangiogenesis occurs from preexisting blood vessels in a tightly regulated manner, which then undergoes remodeling and maturation to form the extensive lymphatic network. However, aberrant lymphangiogenesis is also associated with a number of pathological conditions, such as inflammatory diseases, allograft rejection, and cancer metastasis, while insufficient lymphangiogenesis underlies the debilitating condition of lymphedema. This chapter aims to provide an overview of the different cellular mechanisms and key molecular players involved in the regulation and progression of normal lymphatic vascular development (or physiological lymphangiogenesis) and pathological lymphangiogenesis. Understanding the mechanisms of lymphatic vascular development or its role in these pathological processes is a prerequisite for the efficient development of key therapeutic interventions for lymphatic-associated diseases.