The light microscope, in many of its configurations, is a somewhat complex tool with many adjustable components. Good alignment is essential for good image quality, especially so for quantitative studies. In this chapter we will try to provide a few simple guidelines for the best alignment of all those components of the light microscope which can be focused and/or centered. A better understanding of the function of these components and how their control influences the image has become even more critical for electronic imaging. While analog or digital image processing can, to a small extent, compensate for poor mechanical and optical alignment, the best end result, free of artifacts, is derived from the best possible optical image. When all the microscope's controls are routinely set correctly, the video image will be at its best.