Environmental pollution is recognized as one of the major causes involved in amphibian global declines, in spite of which amphibians are not considered in risk assessment of some pollutants like pesticides, being supposedly protected through data retrieved from other vertebrate taxa. This proposal has two focuses; on the one hand, I will identify the impact of pesticides on amphibian populations using novel, ecologically relevant endpoints indicative of population status and viability, such as reproductive behaviours, immune response and pathogen resistance. On the other hand, I will use these ecologically relevant endpoints to check whether protocols of risk assessment of pesticides are effective in protecting amphibians and reptiles from their impact; with this purpose I will compare the pesticide effects on native amphibians and reptiles based on reproductive, immunological and behavioural studies, with effects on surrogate taxa. A field monitoring in areas of pesticide use will serve to characterize the exposure in realistic scenarios. The relevance of the proposal lies in that it i) deals with a recognized major environmental problem (i.e. amphibian and reptile declines) from the perspective of multiple stressors, ii) presents a clear multidisciplinary scope combining zoology, ecology, toxicology, immunology and analytical chemistry, iii) shows many possibilities for transfer of knowledge to governmental agencies through the identification of relevant guidelines for conducting pesticide risk assessment, and to the industrial sector through the development of the best models to be used in such risk assessments; and iv) has potential for further development as validated models will be useful in extended taxonomical, geographical or chemical scales