The book focuses on the following issues: Uncertainties in the process of model development, such as design, analysis, documentation, and communication, The availability of data and background information needed for optimal modeling, The limited knowledge of modeling, The lack of confidence in the outcome of ecological models and their reliability in pesticide risk assessment, It also suggests future solutions to these challenges, including: A guidance document on the modeling process, Case studies that show how ecological models can provide reliable ecologically relevant risk assessments, Training the people who generate or evaluate results obtained by ecological models, Focusing on ecological models, such as unstructured population models, stage-structured matrix models, and individual- or agent-based models, this volume helps regulatory authorities, manufacturers, and scientists assess the risk of plant protection products in nontarget organisms.