This study suggests that Intermediate High and Advanced speakers produce aspectually valid constructions in Oral Proficiency Interviews (OPIs) in large part because they are doing more than assigning aspect to lexical categories (Lexical aspect hypothesis), but because they are assigning lexicalized meaning to discrete verbs, for example "govorit" (imperfective)--"to talk," but "skazat" (perfective) "to say." Analysis of the data from 55 OPIs conducted with second language (L2) Russian speakers ranging from Intermediate High to Superior confirms three hypotheses: (a) the proportion of aspectual utterances that owe their correctness to lexicalization decreases as proficiency increases; (b) aspectual competence as demonstrated by the greater number of aspectually non-lexicalized verbs in the speech of L2 Russian speakers rises with proficiency level; (c) a decrease in the proportion of lexicalized verbs in an examinee's speech correlates positively with an increase in the variety of verbs used. Other findings include a relative paucity of unprefixed verbs of motion in the corpus and a high ratio of lexicalized forms of skazat "to say," and their distribution did not correlate with proficiency levels in either direction. The high ratio of aspectually lexicalized items in the corpus and the aspectual inaccuracies to which they lead have implications for teaching students who are approaching Intermediate High and Advanced levels of proficiency.