New data for the resistivity‐dopant density relationship for boron‐doped silicon have been obtained for boron densities between 1014 and 1020 cm−3and temperatures of 296°K (23°C) and 300°K. For dopant densities less than 1018 cm−3, results were calculated from resistivity and junction capacitance‐voltage measurements on processed wafers. For more heavily doped material, boron densities were obtained from the nuclear track tecnnique and from Hall effect measurements on specimens cut from bulk silicon slices. The Hall factor was assumed to be 0.8 in the calculation of hole density. The results differ significantly from the commonly used Irvin curve for boron densities greater than 1016 cm−3 with a maximum deviation of 45% at . The data are in better agreement with the Wagner curve, but for boron densities less than 1017 cm−3, the measured resistivities were always higher than those predicted by the Wagner expression. Least squares fits to analytical expressions were determined for the resistivity‐dopant density product as a function of resistivity and of dopant density for temperatures of 23°C and 300°K. Similar fits were obtained for the calculated hole mobility as a function of resistivity and of hole density.