A novel approach is proposed to quantitatively assess the environmental risks associated with the use of plant protection products. Different ranking indexes for the classification of pesticide risk in various environmental systems at different time and space scales have been developed: PRIHS-1 and PRIHS-2 (Pesticide Risk Index for Hypogean Soil Systems), PRIES-1 and PRIES-2 (Pesticide Risk Index for Epygean Soil Systems), and PRISW-1 and PRISW-2 (Pesticide Risk Index for Surface Water Systems). Such indexes identify the risk for each environmental system immediately after a pesticide spraying (PRIHS-1, PRIES-1, and PRISW-1) or in a wider time--space scale scenario (PRIHS-2, PRIES-2, and PRISW-2). Moreover, a general index (ERIP: Environmental Risk Index of Pesticides) was developed for quantifying the comprehensive risk for the environment. The indexes were calibrated by applying to a large number of pesticides for which data were available. The results of the different indexes are compared and the value and limitations of the approach are discussed.