The recent research activities in Beam Physics Lab at Yale University will be presented in this talk. Advancement in accelerator science and technology is required to make possible new discoveries in elementary particle physics. The Yale Beam Physics Lab carries out theoretical and experimental programs on novel means of high gradient particle acceleration, including a detuned-cavity collinear two-beam accelerator and a multi-harmonic cavity accelerator structures.  RF breakdown suppression phenomena in multi-harmonic cavities are also studied. For experiments on these and related topics, we are currently building test facilities for studying high-current beam driven acceleration, multi-band RF driven accelerator structures, and a high-power rf source for tests relevant to the future International Linear Collider ILC. We are also applying techniques of beam physics to develop a novel energy/momentum spectrometer for electrons near the end-point of tritium beta decay for a neutrino mass measurement, and to develop a tunable mono-energetic positron beam for characterizing liquid scintillator response to positrons for neutrino physics application.