Five geodetic arrays located along the San Andreas fault have been surveyed frequently over the 1980-1991 interval to detect possible fluctuations in the deformation rate. There are coherent low-amplitude (within the observational error) fluctuations apparent in some of the measured distances. Those fluctuations need not be tectonic effects but rather may be either random patterns or artifacts introduced by systematic drift in instrument calibration or wander of the geodetic monuments. It is concluded that the measurements are consistent with steady deformation of the arrays over the 1980-1991 interval, and convincing evidence is found in the data for fluctuations in the rate of deformation.