Abstract : The extremely strong fields produced by focusing powerful laser pulses into minute volumes of material enable relativistic effects to be used to generate radiation, to accelerate particles, and to produce electrons and positrons from vacuum. From applications using existing high-repetition-rate lasers to those projected for super intense systems, the individual and collective behavior of electrons is the hub of both practical and theoretical directions. This report reviews work directed toward the application of positron generation from laser interaction with matter and vacuum. It spans funded original experimental research in laser-plasma interaction, where electrons dominate energy transport and MeV/micrometer fields are revealed, to theoretical collaborations exploring the connection between present and foreseeable lasers to the quantum electrodynamics of radiating electrons and electron-positron pair production from vacuum.