The rural development plans in Europe, within the provisions of Axis Two of the Common Agricultural Policy, consider the opportunity to protect and enhance “environmental-friendly” farming systems. The present paper describes the role of organic farming measures in the promotion and safeguard of the High Nature Value in Tuscany. Using National Census of Agriculture data (2010) a Probit model was adopted, in order to estimate the probability of program enrolment. After that, both control and treatment groups were constructed implementing a Propensity Score Approach: selecting 13 explanatory variables which are presupposed to be independent from the outcome variable, the two groups were built on the basis of the propensity scores. The aim should be to have two similar groups, for which the only difference is the treatment itself. In our study the treatment variable is the total area under organic agriculture, while the outcome is the High nature Value. After having controlled and achieved a good balancing between the covariates, the mean effect of the program participation on the treated (ATT) was computed. It is obtained as a difference between the averages of the two groups. The result unexpectedly reveals that AES have not a statistically significant impact on both fauna and flora biodiversity. However, these results must be interpreted with caution because both the type of data (we used cross-sectional data) and the assumptions on which the methodology is based could have a relevant effect on the final outcome.