This paper introduces a new representation for describing routine tasks, called temporal task footprints. Routines are characterized by their temporal regularity or rhythm. Temporal pattern analysis (T-patterns) can be used to isolate frequent recurrent patterns in routine tasks that appear repeatedly in the same temporal configuration. Using tf-idf statistics, each task can then be defined in terms of its temporal task footprint, a ranked list of temporal patterns along with their typical frequencies. Experimental evaluations using data of 29 days observing and logging 10 subjects showed that temporal task footprints of application windows, email and document usage outperform decision tree and SVMs in recognizing the subjects' tasks. Categories and Subject Descriptors