This chapter addresses model specifications for the co-evolution of a social network and a discrete ordinal (or dichotomous) behavior variable. As before, this is done by means of an evaluation function composed of effects. Effects here are functions of the behavior, possibly also the network, as seen from the focal actor. Change statistics here are defined as changes in the value of the effect when the behavior variable is increased by one unit. The chapter defines several effects: first, depending only on the behavior of the focal actor; subsequently, depending on the behavior as well as the network. The latter kind of effect represents social influence or generalized social influence. Before such effects are proposed, it is mentioned that three basic aspects of social influence must be chosen: the reference group, the mechanism of social influence in a dyad, and aggregation over multiple dyads in the reference group. For the mechanism of social influence, a distinction is made between distance reduction (assimilation) and correlational influence. Effects are mentioned for both.