Research on restorative environments has frequently compared the restorative potential of natural and built environments, and showed a higher impact of the former on human psychological functioning and well being. In addition to the psychological outcomes of being in contact with restorative environments, the process and mechanisms leading to restoration in nature are a relevant issue for psychological research in this field. The role of biodiversity might also be important in this respect: it is arguable that biodiversity richness is a relevant feature positively related to the restorative potential of natural settings.In a first study, five typologies of urban and peri-urban green spaces in Italy were identified, ranging from a minimum of biodiversity and a maximum of man-made elements to a maximum of biodiversity and a minimum of man-made elements: an urban plaza with green elements, an urban park, a pinewood, a botanic garden, a peri-urban natural protected area.A convenience sample (N = 696) was contacted in four different Italian cities. Self-reported measures of individual’s experience in the environment (length and frequency of visits, activities performed, perceived restorativeness, affective qualities of the place, perceived well being during and after the visits) were taken through a paper and pencil questionnaire. The relationship between individual exposure to green spaces and perceived well being, as well as the mediating role of perceived restorativeness and affective qualities upon this relation was tested. Results showed that perceived restorative properties are the highest in the peri-urban green areas, and significantly increasing as a function of biodiversity levels. Results also confirmed that frequency and duration of visits positively predict self-reported well being, and as expected, this relation is mediated by perceived restorativeness and positive affective qualities of the settings.In a second study, we aimed at replicating these findings through a laboratory experiment. Subjects (N = 178) from the same four cities were presented with pictures taken from the same five settings of study 1. In addition, measures of also other possible psychological correlates were also taken (e.g., pro-environmental values, attitudes, connectedness to nature, place attachment). To check for the role of familiarity, subjects were also asked to assess pictures taken from five similar settings located in a different city. Results confirmed the pattern emerged in the first field study, and showed also the role of the other social psychological factors considered. The theoretical and practical implications are discussed.