The paper describes the design of a novel multimodal corpus of spontaneous multiparty conversations in Swedish. The corpus is collected with the primary goal of investigating the role of breathing and its perceptual cues for interactive control of interaction. Physiological correlates of breathing are captured by means of respiratory belts, which measure changes in cross sectional area of the rib cage and the abdomen. Additionally, auditory and visual correlates of breathing are recorded in parallel to the actual conversations. The corpus allows studying respiratory mechanisms underlying organisation of spontaneous conversation, especially in connection with turn management. As such, it is a valuable resource both for fundamental research and speech techonology applications.