This pilot study aimed to test the well-being effects of a locally developed mindfulness-based program tailored for New Zealand elementary school children in comparison with an active control condition. It was hypothesized that significantly greater well-being change scores would be observed for the mindfulness group. Students (n = 106) between 9 and 11 years old were allocated by their classroom to either the 8-week mindfulness-based program or an 8-week emotional literacy program. Self-reported well-being and mindfulness measures were collected at baseline and upon program completion. Measures were administered at 12 weeks postprogram to the mindfulness group only. One-way analyses of covariance were used for the main analyses, with corresponding baseline scores entered as covariates. Both programs led to significant increases in well-being outcomes, but significantly greater changes were observed for the mindfulness group (general well-being covariate-adjusted change scores were 4.49 [SE = 0.64] for the mindfulness-based program vs. 2.63 [SE = 0.63] for the emotional literacy program). Mindfulness scores significantly increased for the mindfulness group only. There was evidence of student acceptability of the mindfulness-based program and some indication of sustainability of effects at 12 weeks. The study adds to previous research that highlights beneficial well-being effects of mindfulness-based interventions in the classroom. Further research should evaluate potential long-term effects and delivery training.