While research has reported generally enthusiastic results regarding L2 blogging, some studies have found contrasting blogging experiences among individual learners. Consequently, this study investigated the factors underlying such discrepancies by exploring 33 EFL learners' experiences of participating in a blog project at a Taiwanese university. The students wrote personal blogs and responded to each other over a ten-week period. Data was collected through a questionnaire and individual interviews with 10 of the students. Drawing on a sociological approach, specialization codes of legitimation (Maton, 2007, 2014), the study found salient differences in the students' educational beliefs and practices, which appeared to be linked to their positive or negative blogging experiences. By analyzing the relations between the pedagogical design, learners' existing educational dispositions, and their blogging experiences, the study argued that the blog project assumed learners of a certain type--those who recognized themselves as "knowers" in terms of their blog content--while disadvantaging others who did not possess this attribute. Practitioners are therefore advised to exercise caution when designing blog activities.