The sensitivity of an experience-sampling measure of meditators’ ability to maintain attention to their breathing during 15-min practices of mindful breath awareness meditation, referred to as “Meditation Breath Attention Scores” (MBAS), was previously shown to vary with other meditative experiences and mindfulness-related traits. The objectives of the present study were to assess: (1) the test–retest reliability of MBAS and (2) the sensitivity to practice-related effects of MBAS. Participants completed as many as four meditation sessions held on average 8–10 days apart. Ninety-five participants took part in session 1, with 77 (81 %) completing all four sessions. Test–retest reliability of MBAS was established (mean r between sessions = 0.50) and MBAS were sensitive to practice effects (η 2 = 0.20) consistent with their interpretation as a performance measure. Individual differences in MBAS thus appear to be reliable over time but improve with the repeated practice of meditation. Future research directions are discussed.