The (2+1) resonance-enhanced multiphoton ionization spectrum of phosphorus atoms is reported for the wavelength range 300-317 nm. Atomic phosphorus is formed by multiphoton photodissociation of phosphorus tribromide vapor. Photoelectron spectroscopy conducted at phosphorus ionization resonances produces pure populations of P+(P-3(J)) and P+(D-1(2)) ions. Production of a mixture of phosphorus ionic states indicates a clear propensity to preserve the ion core electron configuration upon ionization of phosphorus. Four spin-changing transitions are assigned supported by photoelectron spectral data.