Zinc and magnesium organometallic reagents are intimately linked with the development of synthetic organic chemistry. They play a fundamental role in a vast variety of synthetic transformations used in research laboratories as well as in the chemical industry. This chapter covers the most important preparative methods for the generation of functionalized aryl- and heteroarylmagnesium and -zinc organometallic reagents. These methods, including metal insertions, halogen/metal exchanges, transmetalations and directed metalations, are discussed in detail. Typical reactions with electrophilic reagents, such as addition, substitution, and cross-coupling reactions are presented. An additional section is dedicated to the generation and use of zinc and magnesium organometallics in continuous-flow.