Abstract:Protected areas' overall goal is to achieve the long-term conservation of natural and associated cultural goods and services. However, effective long-term conservation of natural and associated cultural resources cannot always be guaranteed by a protection regime or even by effective management, as it is usually assumed. The ultimate goal of assessing protected areas is therefore concerned less with management effectiveness than with their overall long-term effectiveness. This paper describes the methodology underpinning the System for the Integrated Assessment of Protected Areas (SIAPA). The aim of SIAPA is to make the concept of 'effectiveness' operational when applied to protected areas. It is an innovative, horizontal site-level assessment system for evaluating integrally and comparably the effectiveness of terrestrial protected areas, as the assessment is based on the same parameters. Indicators are the basic assessment units. They were weighted by an expert panel and integrated into six categories (indexes) defining the effectiveness of protected areas: state of conservation, planning, management, social and economic context, social perception and valuation, and threats to conservation. These indexes were subsequently integrated into a single super-index: an effectiveness index for the protected area. Two alternative models of the SIAPA were developed: the complete model, containing 43 indicators, in order to maximize the amount of information on each protected area; and the simplified model, containing 28 indicators, in order to maximize the cost-effectiveness of the assessment.