The understanding of our relationship with the built environment continues to evolve. The sustainability movement of the 1970s encouraged construction that conserved earth’s limited resources. In the 1990s, universal design motivated us to create accessible and multi-generational abodes. Now, the psychological ecosystem services movement is exploring the connection between urban environments and mental health. According to the World Health Organization, “one in four people in the world will be affected by mental or neurological disorders at some point in their lives. Around 450 million people currently suffer from such conditions, placing mental disorders among the leading causes of ill-health and disability worldwide.” While treatments are available to address mental health from the inside out, fostering mental well-being from the outside in is also a viable supplement. By understanding how urban spaces affect our mental well-being, we may minimize negative outcomes. Thought leaders Greg Bratman and Agnes van den Berg represent two generations that are forging the path towards urban spaces that nourish the mind. Psychological ecosystem services is a budding field of environmental psychology. Greg Bratman is a PhD candidate in the Emmett Interdisciplinary Program in Environment and Resources at Stanford University. He seeks evidence for the impact of nature experiences on cognitive function, mood, and emotion regulation. The results of his research will be incorporated into urban design and decision-making. Bratman explains, “This knowledge can inform the ways in which urban planners incorporate nature into cities, and provide accessible natural landscapes for urban and suburban residents.  It can also provide support for the conservation of open space and wilderness areas in policy design.” For his recent study, Bratman analyzed the rumination patterns (repetitive thought focused on negative aspects of the self) of 38 people. The participants recorded their current levels of rumination and...