A sensor array comprising six functionalized poly(p-phenyleneethynylene) polymers was constructed and used to detect and identify protein analytes. The presence of proteins alters the fluorescence properties of the polymers, generating a distinct fluorescence response pattern for a given protein. Linear discriminant analyses accurately differentiate the patterns of 17 proteins at nano-to micromolar concentrations. An identification accuracy of 97% was obtained on the basis of the tests with 68 unknown protein samples from the training set.