Mindfulness-based cognitive therapy for children (MBCT-C) is a manualized group psychotherapy for children ages 9-13 years old, which was developed specifically to increase social-emotional resiliency through the enhancement of mindful attention. Program development is described along with results of the initial randomized controlled trial. We tested the hypotheses that children randomized to participate in MBCT-C would show greater reductions in (a) attention problems, (b) anxiety symptoms, and (c) behavior problems than wait-listed age and gender-matched controls. Participants were boys and girls aged 9-13 (N = 25), mostly from low-income, inner-city households. Twenty-one of 25 children were ethnic minorities. A randomized cross-lagged design provided a wait-listed control group, a second trial of MBCT-C, and a 3-month follow-up of children who completed the first trial. Measures included the Child Behavior Checklist, State-Trait Anxiety Inventory for Children, and Multidimensional Anxiety Scale for Children. Participants who completed the program showed fewer attention problems than wait-listed controls and those improvements were maintained at three months following the intervention [F (1, 1, 18) = 5.965, p = 0.025, Cohen's d = 0.42]. A strong relationship was found between attention problems and behavior problems (r = 0.678, p less than 0.01). Reductions in attention problems accounted for 46% of the variance of changes in behavior problems, although attention changes proved to be a non-significant mediator of behavior problems (p = 0.053). Significant reductions in anxiety symptoms and behavior problems were found for those children who reported clinically elevated levels of anxiety at pretest (n = 6). Results show that MBCT-C is a promising intervention for attention and behavior problems, and may reduce childhood anxiety symptoms.