In this chapter, the basic metamaterial characterization techniques via the microscopic response of its consisting particles in microwave frequencies are systematically provided. First, the multipolar expansion of a particle’s electromagnetic response is generally analyzed, and the link between dipole terms and respective polarizabilities is addressed. Then, the main polarizability retrieval techniques for small scatterers are discussed. Finally, different characterization methodologies for bulk metamaterials and metasurfaces through consisting particle polarizabilities are presented for both quasi-static and higher frequency regions.