This study analyzes a subset of data from chat logs and transcribed voice chats from a previous investigation by Sotillo (2005) of exchanges between tutors and English as a Second Language (ESL) learners as they collaborated on four learning tasks in an instant messaging environment, Yahoo! Instant Messenger (YIM). Given the characteristics of learner-interlocutor exchanges and negotiation work documented by previous Second Language Acquisition (SLA)/Computer-Mediated Communication (CMC) researchers (e.g., Blake, 2000; Jepson, 2005; Smith, 2003), this study focuses on the characteristics of repair work in language-related episodes, type and quality of negative feedback, and learner uptake. The purpose of this study is to identify how learners notice linguistic forms (both erroneous output and target-like linguistic forms) during naturally occurring negotiation work in an online environment using voice and text-based chat.