The purpose of this paper is to report on a usability study for ESL websites conducted to gain insights from learners of English as a second language (ESL) as they interacted with specific sites. Five carefully selected ESL sites were tested by 10 different users generating a total of fifty testing sessions. Two major research questions guided the study: (a) what are intermediate-level ESL learners' perceptions of the design features for the specific ESL websites? and (b) what design features contribute to learning from the ESL websites? Participant reactions to site specific learning tasks and evaluative questionnaires provided evidence of design features relevant to the ESL context. The findings address information, interface, and interaction design issues as well as highlight the importance of (a) organizing the site meaningfully, (b) recognizing the users' prior knowledge to identify unambiguous labels and categories, (c) making the site easy to navigate, and (d) aligning learning activities or tasks with how ESL learners learn. Results of the study provide implications of the usefulness of ESL websites, the effectiveness of site design features, and the degree to which sites meet ESL learners' needs. (Contains 4 tables, 19 figures and 1 note.)