The ability to recognize human activities from sensory information is essential for developing the next generation of smart devices. Many human activity recognition tasks are from a machine learning perspective quite similar to tagging tasks in natural language processing. Motivated by this similarity, we develop a relational transformation-based tagging system based on inductive logic programming principles, which is able to cope with expressive relational representations as well as a background theory. The approach is experimentally evaluated on two activity recognition tasks and compared to Hidden Markov Models, one of the most popular and successful approaches for tagging.