Many environmental, agricultural, and ecological water quality problems would be better understood and effectively managed if they could be efficiently and economically observed over time in a spatially distributed manner. Unfortunately, the current selection of commercially available chemical sensors is limited, and those that are available are relatively expensive ($200 to $500 ea.), and are generally not optimally packaged for field deployments. Over the past four years, the CENS Sensor group has directed substantial efforts at creating sensitive, selective nitrate sensors with modest power requirements and that are amenable to micro-fabrication methods which will allow the production of large numbers of small sensors. This poster highlights the results of these efforts with respect to (1) potentiometric and (2) amperometric nitrate microsensors. Prototypes of both types of sensors have been successfully tested in the laboratory, using real environmental samples. The potentiometric sensor has been tested in situ in both soil and river systems.