Thin metal films such as Al, Pt and Au are often used in their pure state in microelectronics and MEMS applications. This is true despite the fact that their mechanical behavior is frequently critical for performance. When thin film alloys are employed, a specific alloy composition is often selected because it is a preexisting combination found in a particular fabrication facility, not because it is the optimum composition for the application at hand. In contrast, bulk metals are almost always alloyed for mechanical and microstructural stability, and the effects of various alloying elements are well characterized. Should a designer of microelectronics and MEMS applications need a particular set of mechanical properties (e.g., fatigue or creep resistance) there is no available equivalent understanding of alloy effects in thin film form. In this presentation, systematic experiments focused on elucidating the effects of alloying on thin film mechanical properties will be described. In particular, deviation from (or agreement with) bulk behavior will be discussed for several metal alloy systems.