Monocytes and macrophages are key players in the pathogenesis of atherosclerosis and dictate atherogenesis growth and stability. The heterogeneous nature of myeloid cells concerning their metabolic and phenotypic function is increasingly appreciated. This review summarizes the recent monocyte and macrophage literature and highlights how differing subsets contribute to atherogenesis. Monocytes are short-lived cells generated in the bone marrow and released to circulation where they can produce inflammatory cytokines and, importantly, differentiate into long-lived macrophages. In the context of cardiovascular disease, a myriad of subtypes, exist with each differentially contributing to plaque development. Herein we describe recent novel characterizations of monocyte and macrophage subtypes and summarize the recent literature on mediators of myelopoiesis. An increased understanding of monocyte and macrophage phenotype and their molecular regulators is likely to translate to the development of new therapeutic targets to either stem the growth of existing plaques or promote plaque stabilization.