A major goal of our research is to develop an implantable device for routine amperometric recordings of l -glutamate and other neurotransmitters in the mammalian central nervous system. Specifically, we wanted to develop a microelectrode that is (1) mass produced such that other laboratories can easily utilize the same recording technology, (2) designed to study multiple brain regions and neurotransmitters in various in vitro and in vivo systems, and (3) configured for “self-referencing” recordings, which allows for measurements of resting or tonic levels of neurotransmitters, cross-checking of the selectivity of the microelectrode measures, and improved signal-to-noise ratio by noise subtraction. The present chapter documents our current capabilities of measuring l -glutamate and several other neurotransmitters with rapid temporal resolution using mass-fabricated microelectrode arrays formed on ceramic. We have routinely demonstrated that these electrodes have fast temporal resolution (<1 s), excellent spatial resolution (microns), and low detection limits (≤200 nM) and cause minimal damage (50–100 μm) to surrounding brain tissue. While not a comprehensive assessment of the technology, this chapter contains a large amount of information regarding the fabrication, use, and potential pitfalls of this technology.