The article discusses the investment of L2 learners in the English language on Facebook that they portrayed through their Facebook activities. It studied four informants consisted of diploma students in a Malaysian university. The study consisted of 14 weeks of online observation and semi-structured interviews. Data were collected from online observation and semi-structured interviews. Data were analysed using thematic analysis and Second Cycle Coding. The findings revealed that there were five Facebook activities that were used by L2 learners to improve their English language proficiency: (a) writing posts and comments in English, (b) reading news feeds in English, (c) participating in interest-based Facebook groups, (d) watching movies in English, and (e) communicating with foreign Facebook friends. The most popular Facebook activities were writing posts and comments in English and reading news feeds in English.