The conventional method of calculating static longitudinal stability is improved by taking into account the moment of the fuselage in addition to the wing and tail moments about the center of gravity of an airplane. The general equation for the fuselage moment, which is always unstable or stalling, is derived and presented in terms of the dynamic pressure, the angle of attack and two constants which depend on the shape of the fuselage only. These constants are explained theoretically and approximate values for them are given. These approximations lead to a simplified equation for the fuselage moment which is correct up to an angle of attack of about 12 °, as shown by comparison with existing experimental results. I t is also pointed out, tha t in calculating the fuselage moment for a stability investigation of an airplane, the downwash induced by the wing should be taken into consideration. A static stability calculation is carried through for an airplane for which the total moment about its center of gravity is known from test results. A comparison of theoretical and experimental values shows that the improved method is in much better agreement with tests than the conventional method of stability calculation.