To date, very little research has examined the extrapersonal effects of mindfulness meditation practice. In this study, we investigated whether individual meditation practice exerted an influence on friends or romantic partners. Thirty-five dyads completed an 8-week single-subject protocol using an A-B-A-B design to compare non-meditation phases with meditation phases. One member of each pair was randomly assigned to meditate daily for 15 min during the B-phases of the study; the other dyad member did not meditate in either the A or B phases. Daily diaries for each participant assessed negative affect, positive affect, and facets of mindfulness. For participants in the intermittent meditation condition, meditation was associated with decreased negative affect, increased positive affect, and higher scores on the mindfulness facets of observing, describing, and nonreactivity to inner experience. Results further demonstrated that the negative affect of non-meditating partners decreased during the weeks that their partner meditated and was lower on days that their partner meditated. We did not find similar results for positive affect or mindfulness at the group level. Exploratory analyses suggested that the extrapersonal effects of meditation days on a partner's negative affect might be stronger in romantic couples. This study indicates that 15 min of daily meditation in novice meditators can decrease the negative affect of relationship partners.