The results of a joint project of institutes in the Czech Republic, Hungary, Poland, and the Netherlands on calibration of the 0.01M calcium chloride (CaCl2) soil testing procedure for magnesium (Mg) are presented. In soil samples collected in the participating countries, the analytical procedure for soil research according conventional extraction procedures are compared with data achieved with the 0.01M CaCl2procedure. Linear and quadratic regression analysis were applied to quantify the relations of Mg in the 0.01M CaCl2extract with the different conventional extractants. With the relatively weak extractant, 0.01M CaCl2somewhat lower quantities of Mg are extracted from the soil samples compared to the extraction solutions used in Poland (0.0125M CaCl2), in Hungary [1M potassium chloride (KCl)], and in the Netherlands [0.5M sodium chloride (NaCl)]. With the relatively strong extractant used in the Czech Republic (Mehlich II), more Mg is extracted. The relations of conventional extraction procedures and 0.01M CaCl2for Mg have such high correlation coefficients that direct translation of interpretation tables for the Mg status of soils is considered to be possible.