Ch 4. Separate collection, i.e. source separation, of recyclable materials is crucial for sustainable management of household waste. Functioning and efficient source separation schemes require consideration of the local circumstances and understanding of the influential of behavioural factors pertaining to householders. There are a number of different approaches and technical systems used for source separation. This chapter discusses the role of citizens and presents examples of comprehensive source separation systems. Some recommendations for establishing, monitoring and evaluating separate collection systems concludes the chapter.