Garnet-type Li₇La₃Zr₂O₁₂ (LLZO) is an attractive solid electrolyte material for lithium batteries. Obtaining the desired high conductivity requires formation of the cubic phase. Small amounts of aluminum and/or tantalum have been shown stabilize the cubic crystal structure and increase the conductivity. In this work, aluminum- and tantalum-doped LLZO have been prepared and evaluated with materials characterization techniques and impedance spectroscopy. The dopant additions stabilized the cubic phase and increase the conductivity of the material.