Existing research indicates that instructed learners' L2 proficiency and their metalinguistic knowledge are moderately correlated. However, the operationalization of the construct of metalinguistic knowledge has varied somewhat across studies. Metalinguistic knowledge has typically been operationalized as learners' ability to correct, describe, and explain L2 errors. More recently, this operationalization has been extended to additionally include learners' L1 language-analytic ability as measured by tests traditionally used to assess components of language learning aptitude. This article reports on a study which employed a narrowly focused measure of L2 proficiency and incorporated L2 language-analytic ability into a measure of metalinguistic knowledge. It was found that the linguistic and metalinguistic knowledge of advanced university-level L1 English learners of L2 German correlated strongly. Moreover, the outcome of a principal components analysis suggests that learners' ability to correct, describe, and explain highlighted L2 errors and their L2 language-analytic ability may constitute components of the same construct. The theoretical implications of these findings for the concept of metalinguistic knowledge in L2 learning are considered.