The monograph considers resonance and polarization effects in quantum electrodynamics processes that take place in a strong external magnetic field. A method for analyzing spin-polarization effects has been developed. The factorization of process cross-sections in resonant conditions and the representation of these cross-sections in the form of Breit-Wigner are considered. The possibility of testing these effects in modern international projects to test quantum electrodynamics in strong fields is shown. For researchers, teachers, graduate students, and students of physical and physical-technical specialties.