Recent advances in coring technology and in situ analytical instrumentation have made it possible to assemble large quantities of sediment geochemical data during scientific and mineral exploration cruises. The potential benefit of these improvements cannot be fully realized, however, unless the raw geochemical data can also be reduced and interpreted while the vessel is still at sea. This study involved the development and evaluation of personal computer software designed to meet this need. The software package Q_LM includes a modified Q-mode factor analysis program for use in isolating and quantifying significant geochemical end members that are present in a sedimentary mixture. The Q_LM package also includes a program for determining the relative amounts of any compositional end member present in the mixture; this program is designed to calculate solutions to overdetermined systems of inexact, linear equations using least-squares, linear programming, or Chebyshev (equal residuals) solution criteria. The Q_LM package was successfully tested by evaluating the performance of individual programs versus that of analogous programs run on a mainframe computer. The data sets used in the evaluation included sediment geochemical data from a placer exploration survey at Chagvan Bay, Alaska, and from ferromanganese nodules in the southeast Pacific Ocean.