This paper reports photophysical studies of pyrenylacrylic acid (PAA) and its methyl ester (PAM), along with studies utilizing these fluorescent probes to monitor polymerization rates, Due to the conjugation of the chromophore and the COOH group, the PAA fluorescence band is a mixture of pi-pi* and n-pi* states and changes its structure and spectral position in solvents of varying polarity, from hydrocarbon solvents to aromatic hydrocarbons and polar solvents. PAA also shows two stages of protonation in aqueous solution: protonation on the negative carboxyl group to form the neutral acid, PCOOH, followed by protonation of the carbonyl oxygen to give the protonated. cation, PCOOH2+. These effects are absent in PAM, and only the interplay of the double bond and the pyrene chromophore is observed. Later studies show that fluorescence probing with PAA can also be used to distinguish vicinal and geminal OH: groups on silica gel surfaces, to comment on micelle-water interfaces, and to monitor polymerization of monomers. These probes are convenient for introducing fluorescent chromophores into polyelectrolytes and polymer systems.