Self-study is playing an increasingly important role in the learning and instruction of many subjects, including second and foreign languages. With the rapid development of the internet, language websites for self-study are flourishing. While the language of print-based teaching materials has received some attention, the linguistic and interactional features of websites are largely ignored by educationists, and online learning materials are regarded as simply duplicates of their print-based counterparts. This is far from satisfactory because web-based and print-based materials are very different tools with which participants negotiate their learning activities. This paper examines the linguistic and interactional features of English learning websites in terms of (1) their lexical density/clause length; (2) referential cohesion, particularly the use of personal pronouns; and (3) the presence of involvement strategies and other interactional features. These features are compared with those in textbooks to examine how websites deviate from traditional instructional texts. It is found that both clause and lexical density are greater on websites than in traditional textbooks. Websites make more use of the personal pronouns "I" and "you", whereas textbooks make more use of the authoritative "we". Websites are also more interactional in terms of their use of involvement strategies, imperative structures and modals. These findings highlight the different contexts of textbooks and websites, particularly the different nature of the two channels and their credibility as information sources. This has practical implications for the design of appropriate online instructional resources. (Contains 1 table, 14 figures and 2 notes.)