Chichijima island in the Izu-Ogasawara arc famously has boninite rocks: high magnesian andesites (>8 wt.% MgO) rarely found on land. The Chichijima boninites are pillow lavas and dikes created by submarine volcanic activity between 46 and 48 Ma, soon after subduction of the Pacific plate beneath the Philippine Sea plate began at 52 Ma. Building on recent work in mid-ocean ridge (MOR) settings, we present a unified model of boninite formation that re-interprets boninite occurrence in subduction zones. We infer that the boninites represent the final phase of ocean floor spreading after subduction initiation, with the time lag between basalt and boninite eruptions due to the time necessary for seawater penetration and melting of the upper most mantle. In this unified re-interpretation, we propose that boninites in fact precede the initiation of arc volcanism.