Two key questions for understanding and appreciating the literature on affectionate communication are: What “counts” as an affectionate behavior? and How is affectionate communication measured? This chapter analyzes experiential work on the expression of affection and revisits Floyd and Morman’s (1998) tripartite model of affectionate behavior, which is widely referenced in the literature. Idiomatic expressions of affection are defined in relation to the tripartite model. The chapter also explicates the major operational definitions of affectionate communication used in research – including the Affectionate Communication Index and the Trait Affection Scale – and summarizes their strengths and weaknesses. Finally, various strategies for manipulating affectionate behavior in experimental studies are defined.