This book contains the Proceedings of the Eighth Meeting on CPT and Lorentz Symmetry, held at Indiana University in Bloomington on May 12-16, 2019. The Meeting focused on tests of these fundamental symmetries and on related theoretical issues, including scenarios for possible violations. Topics covered at the meeting include experimental and observational searches for CPT and Lorentz violation involving: accelerators and colliders; astrophysical birefringence, dispersion, and anisotropy; atomic and molecular spectroscopy; cavities, oscillators, resonators; Cherenkov radiation; clock-comparison measurements; CMB polarimetry; cosmic rays; decays of atoms, nuclei, and particles; equivalence-principle tests with matter and antimatter; exotic atoms, muonium, positronium; gauge bosons, the Higgs boson; gravimetry; gravitational waves; high-energy astrophysical observations; hydrogen and antihydrogen spectroscopy; lasers, masers; matter-wave interferometry; meson and baryon properties; neutral-meson interferometry; neutrino mixing and propagation, neutrino-antineutrino oscillations; particle-antiparticle comparisons; photon and particle scattering; post-Newton gravity in the solar system and beyond; second- and third-generation particles; short-range gravity; sidereal and annual time variations, compass asymmetries; single-top and top pair production; space-based missions; spin-gravity couplings; spin precession; time-of-flight measurements; torsion and nonmetricity; trapped particles, ions, and atoms. The meeting also covered theoretical and phenomenological studies of CPT and Lorentz violation including: physical effects at the level of the Standard Model, General Relativity, and beyond; origins and mechanisms for violations; classical and quantum field theory, gravitation, particle physics, and strings; mathematical foundations, Finsler geometry.