First‐principles pseudopotential calculations are used in conjunction with extensive experimental data on P and As‐derived acceptor states in ZnSe to develop a microscopic theory of their atomic and electronic properties. A structural model that explains the presence of both shallow and deep acceptor states, the thermal and optical quenching of photoluminescence lines, and the strongC3vsymmetry of the electron‐spin‐resonance (ESR) active state is derived. The primary result of the calculations is that aneutralacceptor possesses two atomic configurations: a metastable effective‐mass state with a small lattice relaxation labeleda0, and a deepA0state with a large lattice distortion which is responsible for most of the observed properties of acceptors in ZnSe. Nitrogen impurities are proposed to give rise to a shallow acceptor state in either the small or large‐lattice‐relaxed limits. Extension of the results to ZnTe is discussed.