The Aviation and Missile Research, Development and Engineering Center has been involved in an Army Technology Objective (ATO) aimed at furthering phased arrays for both tactical seekers and communication links.1'2 The ATO has been pursuing both MicroElectroMechanical Systems (MEMS) and MMICbased phase shifters with an overall goal of of reducing missile seeker costs by 50% based on the missile mission. In a collaborative effort with the Communications-Electronics Research, Development and Engineering Center (CERDEC), the AMRDEC has worked to improve the maturity of Radio Frequency (RF) MEMS devices for use in phase shifters for phased arrays. This paper will demonstrate that RF MEMS have vastly improved in reliability over the past few years. Additionally, background information and most current results of a task to implement a 16-element phased subarray with RF MEMS-based phase shifters will be presented. The slat will be centered at 33.4 GHz and will utilize ?? wavelength spacing between elements. The individual elements will consist of Vivaldi antennas. Taylor Weighting will be applied to lower the overall sidelobes. The background work for this paper was presented at the 2009 IEEE Aerospace Conference. This paper includes that information along with complete documentation of the laboratory evaluation.