The 12th Topical Conference on Atomic Processes in Plasmas continued a biennial series begun in 1977 to provide a forum for researchers involved in areas of overlap between atomic and plasma physics. This interdisciplinary area is essential to progress in basic and applied research in both atomic and plasma physics. The papers in this proceedings volume cover topics in atomic and molecular processes in laboratory and astrophysical plasmas, atomic theory and experiment, atomic data compilation and databases, plasma atomic kinetics, X-ray sources and lasers, inertially and magnetically confined plasmas, z-pinch plasmas, atomic processes in dense plasmas, industrial plasmas, line profiles, and spectroscopic plasma diagnostics.