The goal of this work was to develop an interactionmanagement system for a mobile robot companion. Such a robot posesa number of new scientific questions in comparison to desktopcomputer applications. More specifically, the interactionmanagement system of a robot companion should fulfill the following8 requirements: (1) handle cooperative interaction, (2) enablemixed-initiative interaction style, (3) separate interaction fromdomain task execution, (4) account for situatedness of thecommunication, (5) facilitate recognition of interaction initiatedby users, (6) make use of different modalities in a meaningful way,(7) enable social behaviors, and (8) contribute to the usability ofthe entire robot system. The present work proposes a powerfulcomputational model of multi-modal grounding that fulfills theabove requirements. This model was implemented for the robotcompanion BIRON within two Implementation-Evaluation-Cycles.Valuable insights were gained in the user studies carried out inthese cycles. This book addresses researchers and developers in thefield of human-robot interaction.