Photoluminescence, photoexcitation, and optically detected magnetic resonance (ODMR) spectroscopy have been used to characterize the band gap defect states of native and intercalated lattices of two lamellar chalcogenophosphate materials, Cd2P2S6 and Zn2P2S6. Native Zn2P2S6 crystals exhibit a complex, angle-dependent ODMR spectrum that is interpreted as arising from lattice metal vacancies. Upon UV irradiation below 4 K, the zinc vacancies trap two photoexcited holes to yield a localized S = 1 photoexcited triplet with zero-field splitting parameters D = 15.875 GHz and E = 5.175 GHz. A nearly isotropic ODMR signal without resolved nuclear hyperfine splittings is observed from Cd2P2S6 after intercalation with pyridinium cations. The signal is analyzed in terms of weakly exchange coupled donor and acceptor centers with g approximate to 2.