A better understanding of emotion regulation (ER) within daily life is a growing focus of research. This study evaluated the average use of two ER strategies (cognitive reappraisal and expressive suppression) and concurrent and lagged relationships between these two ER strategies and affect (positive and negative affect) in the daily lives of adolescents. We also investigated the role of the same strategies at the trait level on these within-person relationships. Thirty-three adolescents provided 1,258 reports of their daily life by using the Experience Sampling Method for one week. Regarding the relative use of ER strategies, cognitive reappraisal (M = 2.87, SD = 1.58) was used more often than expressive suppression (M = 2.42, SD = 1.21). While the use of both strategies was positively correlated when evaluated in daily life (p = .01), the same did not occur at the trait level (p = .37). Multilevel analysis found that ER strategies were concurrently related to affect (p < .01), with the exception of cognitive reappraisal-positive affect relationship (p = .11). However, cognitive reappraisal predicted higher positive affect at the subsequent sampling moment ( β = 0.07, p = .03). The concurrent associations between cognitive reappraisal and negative affect vary as function of the use of this strategy at the trait level (β = 0.05, p = .02). Our findings highlighted the complex associations between daily ER strategies and affect of a normative sample of adolescents.