The present invention provides image-forming compositions and photosensitive lithographic plates which are excellent in sensitivity to infrared radiation, latitude of development, treatable area in m.sup.2, and printing durability. Specifically, the present invention provides an image-forming composition comprising (A) a polymeric compound obtainable by the addition reaction of a resinous polymer having one or more phenolic hydroxyl groups with a silane coupling agent of the following general formula (1) or (2), (B) an acid generator, (C) an infrared absorber, and (D) an alkali-soluble resin, and a photosensitive lithographic plate having this image-forming composition applied onto a substrate. ##STR00001## wherein X.sup.1 and X.sup.2 each represent a trimethoxysilyl group or the like; G.sup.1 represents O or COO; R.sup.1 and R.sup.2 each independently represents a hydrogen atom or a methoxy group; R.sup.3 represents (CH.sub.2).sub.m which may have a hydrocarbon side chain; G.sup.2 represents O or COO; R.sup.4 represents a hydrogen atom or a straight-chain or branched alkyl group; and R.sup.5 represents (CH.sub.2).sub.n which may have a hydrocarbon side chain.