This study examines four learner engagement dimensions (behavioural, cognitive, emotional and social) in pedagogical task performance and provides insights into the effects of two task types (information-seeking and direction-giving) and topic familiarity on learner engagement in a semester-long English course. A total of 28 foreign language learners engaged in eight interactive tasks, and all played the roles of both information-receiver and information-provider alternately under familiar and unfamiliar conditions. Seven measures of engagement and an open-ended questionnaire were employed to understand the learners' engagement in the tasks and their emotional responses to them. The results revealed that the information-providers produced more words and also spent more time on information-seeking tasks wherein they would exchange information than on direction-giving ones that required them to ask for and provide instructions or directions. This was the case for topics they were unfamiliar with; however, when they were faced with familiar topics, they produced significantly more words, spent more time, and spoke more elaboratively in direction-giving tasks. The information-seeking tasks elicited positive emotions, but the direction-giving tasks yielded mixed feelings, attaching positive emotions to familiar tasks but negative ones to unfamiliar tasks. The pedagogical implications of these findings are discussed.