How best to operationalize the mindfulness construct requires further research. In two related studies, we examined undergraduates’ self-reported ability to maintain their attention toward the process of their breathing during 10- and 15-min practices of mindful breath meditation, referred to as “Meditation Breath Attention Scores” (MBAS). MBAS were positively correlated with self-reported interest in and awareness of the breath during both 10- and 15-min meditations and negatively correlated with self-reported difficulties maintaining attention toward breathing (i.e., mind wandering) during the 15-min meditation. MBAS were not positively correlated with the Toronto Mindfulness Scale (TMS) measures of mindful “decentering” and “curiosity.” In study 2 but not study 1, MBAS were positively correlated with the five-factor mindfulness trait “Acting with Awareness.” Secondary analyses replicated an association between measures of trait mindfulness and trait difficulty letting go of depressive thoughts, although MBAS and the TMS measures were unrelated with trait difficulty letting go of depressive thoughts. Future research directions are discussed.