Although speech rate has been shown to be an effective way of measuring proficiency of heritage speakers, some heritage speakers are reluctant to produce any heritage language whatsoever. Lexical proficiency is an alternative method that is also effective in measuring proficiency. In a study with heritage Russian speakers, there was a strong correlation between the speaker's knowledge of lexical items (measured using a basic word list of about 200) and the speaker's control over grammatical knowledge such as agreement, temporal marking, and embedding.