The general methodological approach and the main conclusions of a social impact analysis carried out as part of an environmental impact analysis (EIA) of an agricultural development project in an environmentally sensitive lagoon area of Portugal are presented. This shows the importance of a planning attitude, throughout the different stages of EIA preparation, as an effective means to overcome the lack of information relating to the rural restructuring programme and the associated agricultural production programme. Despite the importance attributed to social impact analysis, it is stressed that, the formalisation of SIA as part of, or independent from, the EIA process must be regarded with caution.