A general form of the derivative nonlinear Schro¨dinger (DNLS) equation, describing the nonlinear evolution of Alfve´n waves propagating parallel to the magnetic field, is derived by using two‐fluid equations with electron and ion pressure tensors obtained from Braginskii [inReviewsofPlasmaPhysics(Consultants Bureau, New York, 1965), Vol. 1, p. 218]. This equation is a mixed version of the nonlinear Schro¨dinger (NLS) equation and the DNLS, as it contains an additional cubic nonlinear term that is of the same order as the derivative of the nonlinear terms, a term containing the product of a quadratic term, and a first‐order derivative. It incorporates the effects of finite beta, which is an important characteristic of space and laboratory plasmas.