This paper examines the variation properties of departure time choice behavior by activity type, using a continuous six-week travel survey collected in the cities of Karlsruhe and Halle in Germany in 1999. Total variation of departure time choice is decomposed into five variation components: spatial variation, temporal variation at aggregate level, inter-household variation, inter-individual variation, and intra-individual variation. These variations are first quantitatively analyzed using multilevel modeling approach without considering the influences of explanatory variables. Then, based on the clarified variations patterns, the paper further examines how much of the variations can be captured by explanatory variables. It is confirmed that different activities show quite different variations and among the variations, the intra-individual variation accounts for the largest percentage of the total variation. Model estimation results further underscore the needs of simultaneously dealing with unobserved macro-level variations, especially inter-individual, inter-household and spatial variations, as well as the intra-individual variation, even when the explanatory variables are included in the model. Such quantitative assessment of various types of variations based on the multi-level modeling approach could provide a useful guide for the specification of behavior models, and deepen the knowledge of behavioral variability by going beyond the traditional paradigm which only focuses on a limited set of variations.