Magnetization measurements are reported on twisted multistrand NbTi superconducting composites. Data for copper matrix composites when fitted to the theoretical predictions give reasonable values for the matrix resistivity. Data for a CuNi matrix composite and data on the rate of decay of the magnetization at small twist rates do not agree with simple theory. An explanation based on the presence of an untwisted core removes the disagreement. Finally, the data are plotted to show a linear dependence of magnetization on filament diameter over the range 0.00036–0.015 in.