This paper examines the behavior of predicational adverbs in a learner corpus of English, focusing on an overall distributional pattern, the correlation between adverbial meaning and position, and common error types. Two types of essays (argumentative and narrative) produced by university freshmen at two proficiency levels (beginner and high-intermediate) were selected for analysis from the one-million word Yonsei English Learner Corpus (YELC). Notable findings from the analysis include the following: 1) The high level learner corpus, and the argumentative writings within the same level, contained more predicational adverbs, both in diversity and frequency, demonstrating the role of L2 proficiency and text type in the fluency with which the learners employed predicational adverbs. 2) Knowledge of scopal distinction began to emerge, i.e. the distinction between VP-level and S-level adverbs or between speech acts and evaluative adverbs. 3) Errors involving lexical selection were more common than word order errors, corroborating the observation in previous research that lexico-semantic learning trails behind syntactic learning. Considering both the crucial role of adverbial modification as a key to nuance in communication and the difficulty of acquiring lexical selection, it is recommended that more emphasis be given to the lexico-semantic aspects of adverbs in the L2 classroom.