From a social point of view, creating a new tie is not the direct opposite of dissolving an existing tie. Different circumstances, mechanisms, and points of view may play a role. Therefore, it often makes sense to treat the creation of new ties differently from the maintenance of existing ties. In stochastic actor-oriented modeling, this means that different effects might operate for tie creation and tie maintenance; or the same effects but with different parameters. This distinction, disregarded in the basic model of Chapter 3, is the topic of Chapter 8. The evaluation function of Chapter 3 here is complemented by the creation function and the endowment or maintenance function, for separately modeling the creation and maintenance of ties. A further model extension is that some mechanisms of network dynamics can be better expressed directly in terms of tie changes than in terms of comparing the state of the entire network with or without particular ties. For this purpose, the concept of elementary effects is introduced.