A low-molecular-weight poly(N-acryloyl-N＇-methylpiperazine) (PAMP-L) forms miscible blends with poly(p-vinylphenol) (PVPh) while a high-molecular-weight PAMP-H forms complexes with PVPh in ethanol solutions. The glass-transition temperatures of all the blends and complexes are higher than those predicted by a linear additivity rule. The specific interactions between PAMP and PVPh were studied by Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). FTIR shows that the hydroxyl group of PVPh interacts with both the carbonyl oxygen and the amide nitrogen of PAMP as shown by the development of a low-frequency and high-frequency carbonyl band in each blend and complex. The amide nitrogen and amine nitrogen of PAMP are discernible by XPS. Both types of nitrogens are involved in interactions with PVPh as shown by the development of two additional high-binding-energy N 1s peaks in each blend or complex. All three types of interacting sites of PAMP interact with the hydroxyl groups of PVPh.