This chapter discusses current progress in observing and modeling the vertical profile of mean wind speed, or mean wind profile, in the atmospheric boundary layer over homogenous terrain. For design of civil structures against wind actions, neutral atmospheric stability conditions (adiabatic atmosphere; Sect. 4.1) are generally assumed due to the high wind shear and strong mechanical turbulence in such conditions (see Sect.  2.3 for the concept of atmospheric stability). However, for other applications such as pollutant dispersion modeling and wind energy resource assessment, it is essential to consider both neutral and non-neutral conditions (both adiabatic and diabatic atmosphere; Sect. 4.2). In addition, the best practice of wind-resistant structural design needs to account for the specific shapes of wind profiles in severe windstorms, such as tropical cyclones and thunderstorms (Sect. 4.3).