Spectroscopic measurements of the total contents (TCs) of a number of important atmospheric gases (methane, CO, water vapor, and others) are regularly taken at the Institute of Atmospheric Physics (IFA), the Institute of Experimental Meteorology, and the Research Institute of Physics. Different systems of monitoring gaseous constituents must be intercalibrated to analyze the measurement data obtained in different regions and to use the network of ground-based measurements as a unified system of validating satellite measurements. Special programs on comparisons of the results of independent measurements of the methane TC were carried out at the IFA Zvenigorod Research Station in different seasons of 1997-1998. The basic results obtained from these programs are analyzed in this paper. It is shown that, for consistent results of total methane measurements to be obtained by different methods, their adaptation to the local conditions of measurements and the use of the unified spectroscopic information are of great importance.