For as long as philosophers ignore mind-wandering, they will disregard from one-third to one-half of conscious thoughts. Regrettably, mind-wandering is only seldom addressed in phenomenology. The fundamental ambition of this paper is to offer the first systematic phenomenological investigation of mind-wandering that relies on the classical principles of Husserlian phenomenology. The paper begins with a critique of the dominant conceptions of mind-wandering in contemporary psychology and philosophy. Against such a background, the paper develops a new, phenomenologically-grounded conception of mind-wandering. The (...) paper further focuses on the central resources in Husserlian phenomenology, which can be fruitfully employed in the future interdisciplinary research on mind-wandering. Phenomenological reflections on background consciousness, on pre-predicative experience, on passivity and on self-awareness lie at the center of this analysis. The paper concludes with some reflections on the relation between mind-wandering and daydreaming and on the function of mind-wandering in conscious life. (shrink)