The recent CAP reform introduced new income support instruments much more related on agricultural agents land-use and land-ownership conditions than before. In this perspective the behavioural analysis of land-use and land-ownership decision process seems to be a basic condition to evaluate the efficiency, effectiveness and equity of those instruments, and to understand and to forecast the agents response to these stimuli. The land-use and land-ownership behaviour differs according to various land managers, not only on the base of "economic-productive" conditions, but also on the base of exogenous and endogenous "institutional" conditions, such as the presence of formal or informal contracts, cultural values, intergenerational linkages, family-farm organisation and land-market imperfections and regulations. In this study an analytic methodology is presented together with an explanatory model which both try to show the role and the relationships between the various land-use and landownership driving factors at an agricultural agent level. It is also showed the different behavioural response to the exogenous stimuli coming from the "economic-institutional" environment, in which the agents operate. The model was tested in a Southern Italian region case study. In the first part of the analysis the various "economic-institutional" environment typologies, in which the region is articulated, were detected, on the base of official census data at the communal administrative units level. The Factorial Analysis through the Principal Components Analysis and Groups Analysis, is the analytic methodology used for this aim. In the second part of the analysis two specific "environments" were chosen in which the empirical survey was led at the agricultural agent level. The data coming from the survey were used to test the behavioural explanatory model. The results showed not only some specific "behavioural" paths which may be detected in the two different environments, but also deep differences among the various typologies of agricultural agents inside the same environments, depending on the "economic-productive" size, the presence of strong familiar roles, informal contracts for hiring work and renting land, the specific history of the agricultural agent, the perception of land as a productive factor, an investment good or a "social status symbol". The results are presented in the last part of the article.