A quantitative “cross-language assimilation overlap” method for testing predictions of the Perceptual Assimilation Model (PAM) was implemented to compare results of a discrimination experiment with the listeners’ previously reported assimilation data. The experiment examined discrimination of Parisian French (PF) front rounded vowels /y/ and /œ/. Three groups of American English listeners differing in their French experience (no experience [NoExp], formal experience [ModExp], and extensive formal-plus-immersion experience [HiExp]) performed discrimination of PF /y-u/, /y-o/, /œ-o/, /œ-u/, /y-i/, /y-ɛ/, /œ-ɛ/, /œ-i/, /y-œ/, /u-i/, and /a-ɛ/. Vowels were in bilabial /rabVp/ and alveolar /radVt/ contexts. More errors were found for PF front vs back rounded vowel pairs (16%) than for PF front unrounded vs rounded pairs (2%). Overall, ModExp listeners did not perform more accurately (11% errors) than NoExp listeners (13% errors). Extensive immersion experience, however, was associated with fewer errors (3%) than formal experience alone, although discrimination of PF /y-u/ remained relatively poor (12% errors) for HiExp listeners. More errors occurred on pairs involving front vs back rounded vowels in alveolar context (20% errors) than in bilabial (11% errors). Significant correlations were revealed between listeners’ assimilation overlap scores and their discrimination errors, suggesting that the PAM may be extended to second-language (L2) vowel learning.