Urban agriculture (UA) can fulfil a variety of functions from recreational and ecological ones to promoting health or enhancing food security and it is attested by an extensive bibliography. In the prison environment, the most recognized functions are: i-improving well-being during detention and ii-foresting prisoners for social and professional reintegration by training. Our study aims to characterise the diversity of forms and functions that UA assumes in prisons. It questions the multiple benefits offered by this kind of projects in this particular context and their capacity to reduce socio-environmental inequalities. Semi-structured interviews with 31 stakeholders enabled us to identify the functions, obstacles, and levers of these projects. The initial results of the survey confirm the multiplicity of functions provided by agricultural activities including food production, even though this is not usually the main function expected. While some products are sold to third parties, in many cases the vegetables and fruits produced are also eaten by the gardeners themselves. This increases the possibilities of deciding which food to eat, enhancing knowledge on its production processes. Paid employment was also identified as a possible function of this kind of projects. However, access to green spaces, training and even jobs are generally highly segmented in term of gender, behaviours, and spatial constraints. These activities should not become a source of segregation and exclusion. Consideration needs to be given to the most appropriate layout of existing and future establishments to achieve greater spatial and social justice.