The solid-state decomposition of the beta phase of titanium alloys is a rather complex phenomenon involving multiple competing instabilities which includes phase separation in the beta phase and precipitation of the omega and alpha phases. Interestingly, despite their widespread application, the microstructural evolution and resultant mechanical properties of these alloys are rather poorly understood. Furthermore, recent developments in advanced characterization techniques such as high-resolution scanning transmission electron microscopy and 3D atom probe tomography allow for unprecedented insights into the true atomic scale structure and chemistry changes associated with the instabilities in the beta phase of these complex alloys. Such detailed studies are being carried out on different beta titanium alloys including the Ti-5Al-5Mo-5V-3Cr-0.5Fe (TIMETAL-5553 or Ti-5553) alloy, used in aerospace applications, and the Ti-35Nb-7Zr-5Ta alloy, used in orthopedic implant applications. The results of these studies will form the basis of this presentation.