Described are novel reversible photochromic diaryl-3H-naphtho�2,1-b!pyran compounds having a substituted or unsubstituted, five or six member heterocyclic ring fused to the g, i, or l side of the naphthopyran. The heterocyclic ring contains an oxygen or nitrogen atom and is attached to the number 5, 6, 7, 8, 9, or 10 carbon atom of the naphtho portion of the naphthopyran. Also described are organic host materials containing such compounds. Articles such as ophthalmic lenses or other plastic transparencies that incorporate the novel naphthopyran compounds or combinations thereof with complementary photochromic compounds, e.g., spiro(indoline)oxazine-type compounds, are also described.