Children experience a multitude of benefits in response to interactions with nature. Despite documented effects, children have increasingly spent less time outdoors over the last century and experienced higher rates of physical and emotional illnesses. Although child-centered play therapy (CCPT) is a culturally and developmentally responsive mental health treatment for children, researchers have limited study of environmental structure and materials employed in the therapeutic process of CCPT. In this study, I sought to further research on the integration of nature with CCPT by providing CCPT in an outdoor, contained playroom equipped with traditional CCPT toys and additional nature materials. Participants were 13 children in the southwestern U.S. with parent-reported attentional or self-regulation concerns (9 males, 6 females; ages 5-10, mean age M = 8.0). Parents reported participants' racial identities were 13% Black (n = 2), 13% Latinx (n = 2), 7% Turkish (n = 1), and 67% White (n = 10). Participants received 8 weeks of twice-weekly CCPT in an outdoor playroom. Results of two repeated measures ANOVAs revealed statistically significant improvement in attention on the Brown EF/A Scales and statistically significant improvement in social-emotional competencies on the SEARS-P. Results of this study illustrate the possible benefits of theoretically integrating CCPT and nature and the clinical impacts the novel approach could have on children's attention and social-emotional competencies. The study also provided insight into the viability of providing an outdoor CCPT intervention at a larger scale and some problems that may arise in creating and maintaining an outdoor playroom. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]