Nine phenyl substituted N-phenylmaleimide monomers for photopolymerization studies have been characterized by x-ray crystallography. Structures for N-(2′-t-butylphenyl)maleimide (1), P21/n, a = 10.197(3) A, b = 11.904(4) A, c = 10.496(5) A, β = 100.61(3)° N-(2′-trifluoromethylphenyl)maleimide (2), P21/c, a = 11.763(8) A, b = 10.699(9) A, c = 8.284(5) A, β = 90.02(5)° N-(2′,6′-diisopropylphenyl)maleimide hemibenzene solvate (3), Pc, a = 16.747(6) A, b = 8.552(3) A, c = 12.899(4) A, β = 105.08(3)° N-(2′,6′-diisopropylphenyl) maleimide (unsolvated) (4), C2/c, a = 28.146(10) A, b = 8.434(4) A, c = 12.881(4) A, β = 92.20(4)° N-(2′-bromo-3′,5′-bis(trifluoromethyl)phenyl) maleimide (5), P21/n, a = 8.7115(16) A, b = 16.125(3) A, c = 9.6707(19) A, β = 99.757(15)° N-(2′-phenylphenyl)maleimide (6), P21/n, a = 8.519(4) A, b = 13.742(5) A, c = 11.147(4) A, β = 92.25(3)° N-(4′-methoxyphenyl)maleimide (7), P21/n, a = 9.320(3) A, b = 6.621(2) A, c = 16.059(6) A, β = 99.58(3)° N-(2′-trifluoromethylphenyl)-2-methylmaleimide (8), Fdd2, a = 43.362(12) A, b = 8.202(2) A, c = 12.720(4) A and N-(2′-trifluoromethylphenyl)-2-methanosuccinimide (9), Cc, a = 7.708(2) A, b = 22.191(9) A, c = 7.137(2) A, β = 115.76(2)° are described. Molecules with bulky 2′-substituents show larger rotations between the mean phenyl and maleimide ring planes, and varying degrees of distortion to the imide group.