The presentation will introduce the concept and advances that have been made in active solder joining. Active solders are based in Sn-Ag based compositions that have active elements such as Ti, Ce, Ga and other rare earth elements added. These elemental additions enable active solder alloys to wet and adhere to most metals and ceramics without the need for preplating. Such active solders are also lead free and join in air without the use of flux. The authors will present how active solders have joined many different combinations of semiconductors, ceramics, composites and metals that are being used in the electronic packages. The authors will also present active solder joining of low temperature co-fired ceramics circuits to metal heat sinks for thermal management of high power and high frequency devices is also presented illustrating processing methods and joint quality and microstructure. A range of examples of several developmental and commercial electronic packaging applications will be presented.