The active ingredients of pesticides, which are widely applied in agriculture worldwide, are important contributors to global human and ecological health burden. Modelling emissions and related human toxicity and ecotoxicity impacts of agricultural pesticides in environmental and life cycle assessment is therefore crucial, but also comes with challenges. This chapter provides an overview of how pesticides are currently addressed in emission inventory and impact assessment, along with a case study focusing on emission, exposure and toxicity quantification of four selected pesticides applied to potatoes in a real-life scenario, and details on remaining challenges and ways forward. The chapter discusses the relevance of spatiotemporal variability in modelling emissions and the toxicity and ecotoxicity impacts of pesticides, and how substitution scenarios can be used to identify more sustainable pesticides. Finally, the chapter looks ahead to future research trends in this area and provides detailed guidance on further reading.