Poly( carboxylic acid)s have been used as crosslinking agents for wood pulp cellulose to increase the wet strength of paper. In this research, we evaluated the effects of two multifunctional carboxylic acids, i.e., 1,2,3,4-butanetetracarboxylic acid (BTCA) and poly(maleic acid) (PMA), on the wet strength retention, dimensional stability, wet stiffness, and folding endurance of the treated paper. We observed that the wet strength retention, dimensional stability, and wet stiffness of the treated sheets increase, whereas the folding endurance decreases as the poly( carboxylic acid) concentration applied to those sheets increases. We measured the ester carbonyl band absorbance in the spectra of the treated paper. The linear correlation between the ester carbonyl band absorbance and wet strength, dimensional stability, and wet stiffness indicates that the improvement in the wet performance of the treated paper is directly attributed to the ester crosslinking of the wood pulp cellulose by poly( carboxylic acid)s. The data presented in this article also indicate that FTIR spectroscopy can be used for predicting the performance of the paper crosslinked by poly(carboxylic acid)s.