This study explores foreign language learners' "skills of discovery and interaction" (Byram, 1997) in instant messenger-mediated intercultural dialogue. Five pairs of foreign language learners (five English as Foreign Language learners from Taiwan and five Chinese as Foreign Language learners from the UK) are recruited for participating in the telecollaborative dialogue on each other's cultures. The analysis starts with an ethnographic approach to realize how the specific characteristics of instant messengers (abbreviated as IM) can affect learners' practice of "skills of discovery and interaction" with their online interlocutors in the intercultural exchange.