Building on the cyclical nature of the workweek and on theoretical advances on entrainment, I explored the interplay between positive affect, work engagement and psychological detachment over the course of the workweek. More specifically, my study addressed two questions: are daily fluctuations in positive affect and work engagement entrained (or aligned) to the workweek in terms of rhythm or cycle, and to what extent does psychological detachment facilitate the entrainment of positive affect and work engagement to the workweek? I tested these ideas with 145 employees who provided daily ratings of positive affect, work engagement, and psychological detachment over the course of 10 consecutive workdays. Growth modelling indicated that positive affect followed a curvilinear pattern, reaching its lowest point midweek. Furthermore, multilevel modelling indicated that daily psychological detachment was positively related to daily positive affect. Practical and theoretical implications of these findings are discussed in the conclusion.