Advances in fundamental nanoscience, design of nanomaterials, and ultimately manufacturing of nanometer scale products all depend to some degree on the capability to accurately and reproducibly measure dimensions, properties, and performance characteristics at the nanoscale. Measurement tools and techniques are needed to image and measure in this realm of research, development, and technology. Currently available metrology tools are also beginning to reach the limits of resolution and accuracy and are not expected to meet future requirements for nanotechnology or nanomanufacturing. Clever approaches to this problem need to be developed. Further, even with the vast array of current tools available, the important question is whether or not they are providing the needed information. Revolutionary approaches to the metrology may be required in the near future. This article discusses some of the issues and potential solutions being undertaken in the scanning electron microscope dimensional metrology project at the National Institute of Standards and Technology.