Implicit affective evaluation is the individual capacity to automatically distinguish external stimuli into broad evaluative dichotomies (e.g., good-bad, positive-negative, pleasantunpleasant). Implicit cognition can reveal information that is not available to introspective access or that people might not want to express. While explicit preferences for environmental stimuli have been widely addressed in the field of people-environment studies, few research dealt with implicit environmental preference. Korpela, Klemettila and Hietanen (2002), using the affective priming paradigm, found that reaction times to joy positive and negative vocal stimuli were faster when subjects were primed with natural (high restorative) vs. urban (low restorative) photographic stimuli, respectively. Hietanen and Korpela (2004) found that facial expression of anger were recognized faster after the presentation of low restorative pictures, but did not find any facilitation for happy faces after positive environmental scenes. Schultz, Schriver, Tabanico and Khazian (2004), using a modified version of the Implicit Association Test (IAT) where participants had to associate words belonging to the categories of “self” and “other” to words linked to natural and built environment, showed the existence of an implicit connection with nature. The aim of the present research is to study both the implicit and explicit preference toward natural and built environment, using a standard version of IAT with environmental pictures stimuli. The hypothesis is to find stronger automatic associations between natural environment and positive affects (implicit preference) as well as explicit positive evaluations for natural vs. to built environments. The role of connectedness with nature (CN) is also investigated. A first study involved 21 undergraduate students, aged from 19 to 28 (M 24.6). The material was composed by 5 natural and 5 built environment pictures and 5 positive and 5 negative aesthetic words. Results of the IAT show that participants were faster in associating natural pictures with positive and built pictures with negative words (compatible task; M = 650 ms; SD = 109)) than in associating natural pictures with negative and built pictures with positive words (incompatible task; M = 908 ms; SD = 179), with a significant overall IAT effect of 258 ms (t (19), -6.707; p = .000). In the explicit task we measured preference for the pictures presented on the IAT task, on a 7- point scale. Natural pictures used in the IAT task were preferred to built ones (M = 5.9; SD = 0.9 and M = 3.4, SD 1.2, respectively). Also, participants preferred natural environments in general, compared to built ones (M = 6.4; SD = 0.9 and M = 3.8, SD = 1.2, respectively). A second study, currently in progress, deals with the implicit evaluation of different environmental stimuli varying for the level of restorativeness. Low restorativeness settings (urban built environment, such as buildings, houses, roads); medium restorativeness settings (urban green environments, such as urban parks plus urban artistic Baroque squares, such as Piazza Navona or Piazza di Spagna in Rome); high restorativeness settings (only natural scenes, such as forests, trees, water and hills). We expect reaction times to stimuli evaluation (using the IAT) to vary as a function of the restorativeness level: the association between “nature” and “positive” is reflected in shorter reaction times. At the explicit level, subjects’ connectedness with nature (CN) is also assessed. We expect CN to covary with implicit preference, and also to moderate the relation between restorativeness level and both implicit and explicit preference for nature, with subjects high on CN expressing stronger preference for nature. The theoretical and practical implications of the results are discussed.