Nocturnal animals are difficult to see and follow, especially in dense rainforest conditions. Nocturnal research is fraught with difficulties not encountered by individuals who study animals in the day, from the need for expensive equipment, constant access to power supplies to run lights and potential for increased encounters with dangerous wildlife. The main drawback of nocturnal fieldwork is that it is simply more difficult to find and continuously observe an animal at night. Through hard work and perseverance it is possible to obtain ecological data on lorises and pottos in the absence of radio tracking (e.g. Das et al., 2014; Nekaris, 2001; Pliosungnoen et al., 2010). Much more detail can be obtained, however, through capturing, measuring, collaring and monitoring nocturnal primates. The essential nature of radio tracking for the study of the behaviour and ecology of nocturnal primates has been recognised since the 1970s (e.g. Charles-Dominique, 1977a; Charles-Dominique and Bearder, 1979), and is by most researchers considered a must for thorough research (Sterling et al., 2000). Radio-tracking studies of lorises and pottos remain limited (2000; Millspaugh and Marzluff, 2001). In this chapter, we review the methods for trapping and collaring slow lorises and pottos, as well as provide a case study of the importance of red light for observing their behaviour in a humane and productive manner (see Box 24.1).