This study investigates the concurrent and predictive validity of Power Management (PM), a newly developed online integrative therapeutic assessment. PM consists of a self-report personality inventory, the Relational Modality Evaluation Scale (RMES), a series of self-guided narrative prompts, and a detailed follow-up score-report. The study had three aims: (1) to evaluate the convergent validity of the RMES in relation to the Big Five Inventory-10 (BFI-10) and the Inventory of Interpersonal Problems Short-Circumplex (IIP-SC), (2) to investigate the test re-test reliability of the RMES, and (3) to investigate the therapeutic benefits of PM by comparing it with narrative and mindfulness self-guided interventions over time, on outcome measures evaluating affect, insight, psychopathology, well-being, self-esteem, ability to change, and personal relevance. Aim 3 was investigated using a short-term longitudinal design, in which outcome measures were administered at baseline (before interventions), immediately following interventions (post), and two weeks later (follow-up). The sample was recruited online through Mechanical Turk and at baseline included 82 men and 101 women, mean age = 35.82 years (SD = 9.61). Participants were randomly assigned to one of three interventions: PM (42 men, 56 women), narrative writing (26 men, 25 women), and mindfulness (14 men, 20 women). For Aim 1, partial correlations, controlling for demographics, identified statistically significant relationships between RMES, BFI-10, and IIP-SC subscales predicting personality constructs with high agency and high affiliation, high agency and low affiliation, low agency and high affiliation, low agency and low affiliation, as well as psychopathology. For Aim 2, The RMES showed strong test re-test reliability over a two-week period (r = .84, p < .000). For Aim 3, mixed-model repeated-measures ANOVAs indicated that the PM group had statistically significantly higher scores on outcome measures reflecting increased psychological well-being, insight, and motivation for change compared to the other groups. Scores improved between baseline and post for most psychotherapy outcome constructs across interventions. Gender mostly did not moderate results. Results suggest that PM is a promising therapeutic assessment worthy of further investigation. Mindfulness and narrative writing also showed evidence of effectiveness as delivered in an online format.