[en] The authors performed high-resolution measurements of the Stark-broadened line profiles in a magnesium plasma at known density, and compared the measured line profiles with theoretical predictions. In the experiment, a magnesium sample was heated indirectly by x-rays from laser-production plasma. Both the lateral expansion of the exploding foil and the absorption in the helium-like Rydberg series were measured through the use of point projection spectroscopy. The plasma temperature and ionization distribution were determined from the ratio of the helium-like to lithium-like absorption features. For this experiment, a comparison between plasma density derived directly from radiography and by a careful examination of Stark profiles was accurate to about 40 percent. The experiment will be repeated under more carefully controlled conditions which should allow a calibration of Stark-broadened profiles with an accuracy of order 10 percent