Abstract: A hand tool, and method of using the same, for installing roof gutters on a residence or other building. The tool may be used to position the gutter temporarily against the building wall as the tool is held in one of the user's hands, without any attachment of the gutter or the tool to the building being necessary. The user may use his other hand to hold a hammer to strike the free end of a nail-driving piston--which is held and guided, together with a nail, by the tool--to drive the nail through the rear wall of the gutter and/or the rear portion of the associated hanger, and then into the building wall. The tool may then be freely and immediately moved away from the gutter.