Evaluation of continuous wave chemical laser performance has been accomplished through the investigation of key operating parameters. Various optical diagnostics have been employed to measure output beam quality, jitter, spectral content, total power and power spectral density. Near- and far-field intensity distributions have been characterized. Flow field visualization systems to monitor index variations, small signal gain, and vibrational populations have been examined. Techniques utilizing grating rhombs, scanning spectrometers and infrared cameras will be discussed. Methods employing Fizeau interferometers, probe lasers and chemiluminescence spectroscopy will also be addressed. Data reduction and interpretation of results from these diagnostic techniques will be described.