This report extends and revises LA-2387. Changes in the Los Alamos non- linear least squares program are outlined. A condensed guide for the data card arrangement is presented. The PAKAG code is written in FORTRAN language for the IBM-7090. The system fits a given function to a given data set. The function to be fitted can be any well-behaved'' mathematical function for which the derivatives exist and for which the data set does not give rise to points of singularity. (M.C.G.)