In line with a communicative curriculum for English, it is claimed that communicative competence involves knowledge about when and how to display affectivity in talk-in-interaction. Typically, interjections have been described as a lexical means for expressions of emotion. A survey of textbooks canonical of EFL at German elementary and secondary schools reveals that interjections are often used in (constructed) conversation examples. However, the translations of the interjections given do not adequately account for their meanings and use. Illustrated by a case study on two forms and uses of "oh", it is argued that the approach of Interactional Linguistics can provide an empirical basis for teaching interjections in the EFL classroom. Based on the finding that the competent use of interjections depends on the correct production of the segmental and prosodic form and the timely positioning in a conversational sequence of actions, didactic guidelines for teaching interjections are proposed.