Cyclic polymers possess different properties compared to their linear analogues of the same molecular weight, such as smaller hydrodynamic volumes and higher glass transition temperatures (T-g). Cyclic poly(4-ethynylanisole) (cPEA) was synthesized via a catalytic ring-expansion of 4-ethynylanisole. The catalyst employed was a tungsten complex supported by a tetraanionic pincer ligand. Evidence of the cyclic topology comes from gel permeation chromatography, dynamic light scattering, static light scattering, and solution viscometry. Demethylation of cPEA with boron tribromide affords cyclic poly(4-ethynylphenol) (cPEP-OH). cPEP-OH exhibits pH-responsive water solubility, being soluble in aqueous solutions at elevated pH and becoming insoluble under acidic conditions. The linear equivalent of cPEP-OH was also synthesized, and it exhibits similar pH responsiveness.