An appraisal is made of the current status of measurement in Auger electron spectroscopy (AES) and x-ray photoelectron spectroscopy (XPS). In many areas, the measurement accuracy is now exceptionally high and reproducible. For XPS, peak energy calibration values are presented with a traceable accuracy of 0.02 eV or better. Interlaboratory tests show that commerical instruments, calibrated using two peak energies, reproduce a third in the middle of the energy scale to ±0.035 eV. For selected area XPS instruments, relativistic corrections may be important and these nonlinear corrections are verified to ±0.05 eV. Instrument intensity–energy response functions are analyzed and interlaboratory tests show that relative functions between commercial instruments may be defined, by two methods which agree, to within about 4%. The area of analysis in XPS is defined, with reference methods, to evaluate even the most complex spectrometers. Traceability is then extended to sputter depth profiles. It is shown that a certified reference material of Ta2O5 on Ta may be used to establish depth scales and depth resolutions. Depth resolutions as high as 1.18 nm at 28.4 nm depth are observed. Rationalization of depth resolutions, using a compiled data base, show that the transferability of data allows one to question the validity or universality of conclusions concerning techniques for improving depth resolution.