This article analyzes the phase-averaged hydrodynamics induced by regular wave groups and the related long waves under reflective conditions outside of the wave-breaking zone. The solutions of the inviscid region and wave-group bottom boundary layer (WGBL) are analytically investigated for a regular wave group at a constant depth, impinging obliquely on an alongshore uniform reflective wall. The problem is formulated and solved by using the classical multiple-scale approach. Phase averaging is defined on the basis of the cascade of spatial and temporal scales of the problem leading to a weak unsteady (hydrodynamic) regime (WUR), a steady regime (SR), weak nonhomogeneous regime (WNHR), and homogeneous regime (HR) of instantaneous quantities. The analysis of the inviscid region hydrodynamics shows that depending on the time scale used for the averaging, modulation scales of O(100 m) and O(1 km) may appear in the time-averaged pressure and the free stream velocity fields. These modulations are related to the nonlinear interference of the incoming and reflected wave-group motions. Supermodulation scales of O(10 km) are also possible. Such scales result from the superposition of the bound long waves and the oscillatory free long wave mode released during the reflection of the wave train. The SR of the total pressure field and the WUR of the radiation stresses are also analyzed. The WGBL solution shows that multiple-scale modulation of the inviscid region hydrodynamics can be fully transmitted to the Eulerian drift in the viscous region. We also found that under reflective conditions and nearly normal wave incidence, the WUR of the Eulerian drift may present standing modulated patterns with scales of O(100 m), O(1 km), and O(10 km). In the SR, there can be scales of O(100 m) and O(1 km). The mechanisms which determine the vertical structure and direction of the WUR and SR of the Eulerian drift beneath wave groups are also investigated as a function of the main parameters of the WGBL model. Physical implications of and qualifications to the theory presented on nearshore sediment transport are discussed.