This article focuses on the grammar of Japanese "kara" "because/so" and "kedo" "but", traditionally understood as conjunctive particles whose function is to mark a "subordinate" clause and connect it to a following "main" clause. This article shows that, in conversation, these forms are often used turn-finally without an apparent main clause and that they are grammaticizing into final particles functioning to yield a turn. Then lexicalized uses of "kara" "because/so" exploited for turn continuation purposes are considered, showing that different uses of "kara" "because/so" reflect various stages of its ongoing change. It is argued that the lexicalized independent conjunction "dakara" is developing from a "consequential" conjunctive particle connecting two clauses to an independent "non-consequential" form. This article shows that this non-consequential form is used for giving explanations for an assertion in an immediately preceding turn and for (re)claiming a turn. Findings shed light on the grammar of turn continuation and highlight the diachronically and synchronically emergent nature of Japanese interactants' grammar. (Contains 5 tables and 10 footnotes.)