Methods for forming earth-boring tools include providing a metal or metal alloy bonding agent at an interface between a first element and a second element and sintering the first element, the second element, and the boding agent to form a bond between the first element and the second element at the interface. The methods may be used, for example, to bond together portions of a body of an earth-boring tool (which may facilitate, for example, the formation of cutting element pockets) or to bond cutting elements to a body of an earth-boring tool (e.g., a bit body of a fixed-cutter earth-boring drill bit or a cone of a roller cone earth-boring drill bit). At least partially formed earth-boring tools include a metal or metal alloy bonding agent at an interface between two or more elements, at least one of which may comprise a green or brown structure.