This chapter focuses on two principal generalizations: First, all else being equal, lenition is more likely to occur the more open the segments which flank the target; the commonly observed intervocalic lenition context proves to be a special case of this generalization. Second, all else being equal, lenition is more likely to occur the faster or more casual the speech style. I argue that both phenomena are manifestations of effort-based contexts: that is, lenition occurs more readily in these contexts or under these conditions because greater effort is required to achieve a given constriction target in these contexts/conditions. The claim, then, is that the effort-based approach not only permits a unified characterization of lenition processes, and accounts for some of the restrictions on lenition outputs (i.e. the non-stridency and geminate generalizations of Chapters 4 and 5); this approach also naturally accounts for a broad range of contexts and conditions which figure prominently in lenition typology.