Sociodynamics intends to provide an integrated strategy for mathematical modelling of collective dynamic processes in the human society. The approach is far more general than catastrophe theory: It comprises the full dynamics of key-variables, namely their chance behaviour as well as their quasi-deterministic evolution.It connects the bottom-up and top-down interaction between microlevel and macrolevel of the social system. The design principles start from the elementary dynamics of the key-variables in terms of socially interpretable probabilistic transition rates and end in evolution equations for them: The master equation for the probability distribution over key-variables comprises mean behaviour and fluctuations as well. The quasi-meanvalue-equations derivable from the master equation describe the mean evolution only.