We have measured the width, G, of many P and R lines of the fundamental vibration–rotation band of CO perturbed by N2at 348 K and pressures of about 50 kPa. We have also extended the measurements made earlier at room temperature. Thebroadening coefficients, g 5 G/pressure, were obtained with an accuracy of 0.3% by fitting with a Lorentzian, a Voigt, andan empirical lineshape model that blends together a hard-collision model and a speed-dependent Lorentzian profile. In all casesthe results are represented by an empirical exponential power law polynomial in the line number, m. Combining the data atthe two temperatures yields the exponent n in the scaling law g(T1)/g(T2) 5 (T1/T2)2n, as a function of line number. Thebroadening coefficients and the variation of the temperature exponent line number are compared with theory. In addition, theline-mixing parameters are also reported at 348 and 301 K.