A Weight of Evidence approach was applied to define three integrated effect indexes estimating the impairment on terrestrial ecosystems caused by the stressor(s) of concern. According to a Triad approach, the integrated effect indexes combined the information provided by the measurement endpoints of each line of evidence (chemistry/bioavailability, ecology and ecotoxicology) and allowed to analyse the impairment degree highlighted by each measurement endpoint as difference from the reference condition. Multi-Criteria Decision Analysis (MCDA) was used for the aggregation of the complementary Triad information, including expert judgement and a weighted procedure based on the endpoint sensitivity and the sensitivity of the test for ecosystem effects. The developed methodology was implemented in the DSS-ERAMANIA, Module 2, and is presented in this paper as "Integrated Effect Indexes" (IEI) sub-module. The latter has been preliminary applied to the Acna di Cengio (Italy) contaminated site; the results of this application are presented and discussed.