This study examined the combined efficacy of two promising non-pharmacological treatments for Attention-Deficit/Hyperactivity Disorder (ADHD): a computerized working memory (WM) training program for adolescents (Cogmed-RM), and a behavioral parent training (BPT) program for the improvement of parenting skills for mothers. In a pretest-posttest randomized controlled trial, we considered how selected adolescent and maternal variables changed over time as a function of treatment condition. At pre- and post-intervention, self-report questionnaire data were collected from 91 adolescents (aged 11-15), mothers, and teachers, and neuropsychological measures of WM spans were also administered to adolescents. We used repeated measures ANOVAs and ANCOVAs to test change in outcomes for each of four treatment and active control (placebo) group combinations in a 2 x 2 mixed group factorial design: (1) Treatment Cogmed-RM/treatment BPT; (2) Treatment Cogmed-RM/control BPT; (3) Control Cogmed-RM/treatment BPT; (4) Control Cogmed-RM/control BPT. Primary results indicated that (a) adolescents in the treatment Cogmed-RM groups improved more than those in the control Cogmed-RM groups on most objective neuropsychological measures of WM spans at posttest; (b) overall, parent-adolescent dyads who were in the control Cogmed-RM/treatment BPT group reported the fewest problems on ratings of adolescent WM functioning, maladaptive parenting behaviors, parent-adolescent conflict, and adolescent global functioning outcomes, particularly when using mother reports; (c) a positive adolescent ODD diagnosis moderated several differential treatment effects for parenting behavior and parent-adolescent conflict outcomes, such that mothers of adolescents with ODD showed fewer parenting problems and lower conflict at posttest; and, (d) when there were no interactions among the conditions from pretest to posttest, we found main effects of time on several outcomes (i.e., forward digit span, inattentive and hyperactive/impulsive symptoms, ODD behaviors, and clinical impairment), which indicated that all four groups improved on outcomes over time, regardless of group condition. Overall results suggest BPT is effective for reducing maladaptive parenting behaviors and parent-adolescent relation problems. However, the clearest findings for Cogmed-RM show that the program primarily improved only neuropsychological measures of WM spans. Future research might benefit from sequencing the Cogmed-RM and BPT interventions over time to further understand the effects of each intervention on individual and family functioning.