Abstract: The Ising model in transverse field provides the simplest description of a quantum glass. I study two systems that are realizations of the Ising model in transverse field, LiHo_xY_{1– x}F₄ and Rb_{1– x}(NH₄)_xH₂PO ₄. In the spin glass LiHo_xY_{1– x}F₄, applying a magnetic field H_t transverse to the Ising direction introduces tunneling between the bare Ising eigenstates. In addition, the coupling between the transverse dipolar interaction and the transverse field introduces entanglement or tunable random fields depending on the concentration. By comparing the classical and quantum transitions in LiHo_0.198Y_0.802F₄ and LiHo _0.167Y_0.833F₄, I characterize the crossover from random field dominated behavior in the 19.8% sample to entanglement dominated behavior in the 16.7% sample. The quantum transition in the 19.8% sample is dominated by the limit on its correlation length caused by the random fields, while the dominant effect in the 16.7% sample is the enhanced tunneling rate introduced by entanglement. The proton glass Rb_1–x(NH ₄)_xH₂PO₄ relaxes through tunneling of protons in the hydrogen bonds of the crystal, yielding an effective Ising model in transverse field. Since this field cannot be tuned directly, I combine bulk dielectric susceptibility measurements with neutron Compton scattering measurements of the local tunneling potential in two different concentrations, x = 35% and 72%. I find that tunneling drives the fastest relaxation processes at temperatures as high as 20 K and explicitly calculate the tunneling rate from the tunneling potential of the hydrogen bond. Moreover, the structural mechanism for the glassy relaxation allows a real-space picture of the relaxation dynamics to be correlated to the free energy description of aging. I find that the glassy relaxation is driven by the sequential diffusion of defects called Takagi configurations with a classical to quantum crossover in the relaxation at 3 K. I relate the relaxation rate to the quantum action of tunneling of the Takagi configurations through the lattice.