This article examines the V3 particle så in Fenno-Swedish, where the particle can follow both initial arguments and adjuncts in root clauses. In Mainland Scandinavian, this distribution is rather strictly limited to the latter context. The starting point is that the V3-pattern-triggering så is the ‘general adverbial resumptive’ in copy-left dislocation. In copy-left dislocation, an agreeing resumptive item causes a similar V3 pattern, where the adverbial spell-outs of the resumptive are partially interchangeable with så. Three hypotheses are considered. Firstly, så may have become fully generalised resumptive being interchangeable with all spell-outs. Secondly, the distribution could include all initial elements, also wh-phrases and negation markers, that are not pure operators. Finally, the paper suggests that the phenomenon is partially prosodic, and så satisfies a preference of having an anacrusis in the prosodic constituent including the finite verb.
