This thesis deals with what happens linguistically and interactionally in naturally occurring bilingual talk-in-interaction between Danes and Swedes. In the data – collected within the elderly care in a Danish municipality – three Swedish caregivers interact with Danish pensioners and colleagues. Previous research on inter-Scandinavian interaction has mostly been concerned with talk-in-interaction in arranged situations and/or situations where the participants do not interact regularly with other Scandinavians. The talk-in-interaction in the present data, however, has a clear activity context, and the participants are used to talking to people speaking the neighbour language. The aim of this study was to examine how comprehension, understanding and social affiliation were achieved and demonstrated across differences in language, age, nationality and institutional roles. The theoretical and methodological framework includes accommodation theory and conversation analysis. The linguistic aspects of the Swedish speakers’ accommodation to Danish were studied both in a detailed analysis of accommodation on five linguistic levels, and quantitatively in a study of five linguistic variables. One result was that the Swedish caregivers had individual ways of accommodating their language to Danish. The linguistic analyses also indicated that one reason for this accommodation was to make communication flow more efficiently. A CA-study of other-initiated repair showed that four factors in the interactional situation influenced understanding: context, physical distance and orientation, clearness of speech, and neighbour language and accommodation. It could, however, not be shown that the speakers’ use of different linguistic varieties caused a significant number of problems in understanding, or that the participants frequently oriented to such linguistic differences as part of the problem. Compliment sequences and their role in creating social affiliation were studied in another CA-study. They often played the role of introducing a new topic and leading the talk away from the practical chores at hand, thereby reducing the institutional aspect of the situation. The interactional ways of creating comprehension, understanding and social affiliation are likely to be at least as important as linguistic convergence in achieving these goals.