In this review will be discussed the merits of positron annihilation as compared to “standard” methods such as electron paramagnetic responance, infrared spectroscopy and deep level transient spectroscopy as applied to various semiconductors. In the case of silicon (only) the available detailed knowledge from the “standard” methods will be compared to the positron data addressing the association of lifetime values with specific defect structures such as monovacancies and divacancies. The importance of charged states (Fermi level position), shallow traps and impurity-vacancy complexes will be emphasized. Trapping cross-sections for various defects/charged states will be discussed in the context of electron paramagnetic resonance data.