Although of paramount importance to realistic modeling of the earth's response to climate changes, the dynamics of the stratocumulus-topped boundary layer are still largely mysterious. This study attempts to improve our knowledge about these processes by using mixed layer assumptions to derive entrainment rates and buoyancy flux profiles from data collected aboard the NOAA vessel Ronald H. Brown during the EPIC 2001-Sc campaign. In particular, a diurnal cycle of entrainment, confirmed by both water and energy budgets as well as by a subsidence/cloud top height balance, is presented. Estimates of both mean value and diurnal variation of each term involved in these budgets are calculated and for each budget a dominant balance of terms is suggested. A diurnal composite of buoyancy flux profiles is also created; analysis of this composite suggests that the boundary layer is decoupled throughout much of the day. The onset of decoupling occurs around daybreak and is fueled by an early-morning peak in the diurnal cycle of drizzle. Decoupling is maintained throughout the day by solar radiation. A further indication that decoupling is essential to boundary layer dynamics is presented in the form of mixed layer model simulations, which predict zero entrainment (suggesting breakdown of the mixed layer assumption) throughout much the day when forced to match observed drizzle rates.