An extrusion for a multiple configuration window base frame is disclosed. In one aspect, the frame includes a main body defining an interior-side surface and an opposite opening-side surface extending between first and second ends. To facilitate use with different window types, part or all of the opening-side surface can be formed in a parallel arrangement with the interior-side surface. The frame can include a first attachment arrangement located proximate the main body first end that is configured for attachment to one or more cladding members. In one aspect, the first attachment arrangement includes a first clip member having a first outer portion and a first inner portion that define a first female receiving area and having a first overhang portion extending at least partially across the female receiving area to enable a snap-fit connection between the main body and the cladding member.