The growing importance of assessment through technology in virtual learning environments puts in evidence the role of Social Network Analysis in offering an interesting toolset for educators. Extracting participation data from the virtual environment (such as from forum, e-portfolio or other communitarian tools for information and document sharing), it is possible to construct a social reticle of interpersonal relationships among e-learners. The analysis of the reticle's features helps the teacher to understand the evolution of the virtual classroom and the development of relationships among students in formal settings. Although in formal settings all activities are recorded in the environment and are represented by social reticle, informal learning activities, which happens outside the virtual environment, can be analyzed only in a partial way, in function of the opening degree of the environment and on the basis of the quantity and quality of elements present and recorded in the same environment. The reliability of a social reticle in formal virtual setting is therefore questionable, because the presence of a tutor or a teacher can significatively influence the nature and the development of the reticle itself which can be characterized by relationships that do not match with those that learners can realistically activate outside the virtual environment. Informal setting instead allows the forming and the development of a social reticle more representative of the effective relationships among learners both inside and outside the virtual environment. An interesting solution can be represented by the continue monitoring of a hybrid environment, in which the presence of tutor/teacher is limited and the social reticle is under observation, in order to highlight the stability or instability of relationships as indicator of community's production self-efficacy. This paper deals with the results deducted from a study about social networks of e-learners, both in formal and in informal settings, about parameters that can be considered significant for informal processes assessment. It puts in evidence the degree of reliability of formal social reticles in respect to informal ones, suggesting actions that teachers can do in order to monitor and assure a better performance for their virtual classrooms..