The volume contains the results of a research project funded by the DFG on cross-media usage. A model of media choice is developed, which applies the microeconomic approach to explain the allocation of limited consumption budgets between consumer goods to the allocation of scarce time between media usage activities and non-media activities. The time allocation model is tested using structural equation models estimated with data from the ARD/ZDF long-term study on mass communication and the Media Analysis. The daily available time is divided according to its degree of availability into leisure time, reproductive time, and working time. It shows a varying degree of influence of the available (free) time on the usage duration of individual media types. The strength of short-term substitution relationships is also examined.