The present study explored the effects of different task types on the autonomous vocabulary learning of EFL learners. To this end, two types of tasks with similar but slightly different levels of involvement loads were developed: a corpus-based task and a word map task. The participants of the study were 41 EFL students from a university in Seoul, Korea. They were divided into two groups: a corpus group (n=20) and a word map group (n=21). A total of 33 target words were selected and the experiment was administered during a period of five weeks. Major findings from the study were as follows: First, the corpus task proved to be more effective than the word map task in productive vocabulary learning, whereas the two tasks showed similar effectiveness in receptive vocabulary learning. Second, the two tasks varied in the effectiveness of vocabulary learning depending on the learners' vocabulary proficiency levels and the specific domains of vocabulary knowledge (receptive and productive). Lastly, the corpus group responded more positively than the word map group to their task and to the vocabulary learning. The findings indicate that the corpus task has advantages over the word map task and provide ‘residual’ empirical support for Hulstijn and Laufer’s (2001) involvement load hypothesis. Based on the findings, some pedagogical implications were made for the effective teaching and the autonomous learning of vocabulary.