The phthalide ring was examined as an activating group for nucleophilic aromatic substitution. The proposed mechanism by which activation occurs is through a ring opening of the phthalide ring to form a Meisenheimer-like sigma complex. 3,3-Bis(4-fluorophenyl)phthalide was synthesized and examined under different reaction conditions to determine its suitability for polymer formation. Semiempirical calculations at the PM3 level suggested that 3,3-bis(4-fluorophenyl)phthalide is only moderately activated, whereas H-1, C-13, and F-19 NMR spectroscopy suggested that the monomer was not sufficiently activated for nucleophilic aromatic substitution. However, low-molecular-weight polymers (number-average molecular weight < 7000 g/mol) were produced from bisphenol A, hydroquinone, and phenolphthalein. The polymers were characterized by gel permeation chromatography, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, NMR spectroscopy, and differential scanning calorimetry. The polymers displayed relatively high glass-transition temperatures.