The present invention is directed at methods and apparatus for controlling multi-source heating systems. The multi-source heating systems of the present invention may include two or more heat sources such as a heat pump, a furnace, an electric heating strip, or any other suitable heat source. An illustrative system includes a multi-zone, multi-source heating system. The illustrative system may determine which of the multiple sources to use depending on a number of factors. Some illustrative factors include information about zones calling for heat, external environment information, and information about the heat sources. One of the heat sources may be, for example, a heat pump, and a determination of whether to activate the heat pump may include determining the current heating capacity of the heat pump and comparing the heating capacity to the amount of heat needed to satisfy the current heat calls. Methods for determining which of at least two heat sources to use are also provided. Additional embodiments include methods for controlling multiple-source heating systems, and systems for providing heat with multiple sources.