The damping constants (α-parameter) for Li, Na, K, Mg, and Ca were determined from curves of growth prepared from emission measurements at 0, 1.3, 2.2, and 3 kG. The collisional (Lorentz) half-intensity width Δλ L , the absolute atom concentrations N in the flame, and the effective collisional cross sections Q L have been calculated. They show appreciable increases with magnetic field strength. From the line profiles, it is found that the half-intensity width Δλ 1 2 did not change, while the width at the extreme wings Δλ w has broadened slightly. The kind of perturbers which are thought to play an important role in collisions and the preponderant type of interaction are discussed.