The low-lying electronic states of AlP2, Al2P and their anions and cations are investigated using a complete active space multi-configuration self-consistent Weld technique followed by multi-reference singles + doubles configuration interaction (MRSDCI) calculations. Potential energy surfaces, geometries, energy separations, adiabatic ionization energies, electron affinities, dipole moments vibrational frequencies, zero-point and dissociation energies are computed. While AlP2 exhibits similarity to the heavier analogs, Al2P was found to exhibit a different ground state compared to Ga2P and In2P.