Apparatus for positioning anchor bolts in formwork comprises a main body having a longitudinal slot, one or more bolt holders slidable within the slot and each adapted to hold a bolt, and two abutments slidable within the slot outboard of the bolt holders. The main body may be positioned on the formwork, with the abutments outboard of the formwork, and with the bolt holders in the main body slot. After the bolt holders have been laterally positioned relative to the formwork, with their abutments positioned against the formwork, the bolt holders and abutments may be fastened to the main body, and the main body attached to the formwork, thus holding the bolts in position relative to the formwork. In variant embodiments, either or both of the abutments may fixed to or integral with the main body, as may be the bolt holder.