We used ESM to study interest experience in and across contexts in daily life. This is a valid and reliable self-report measure that can be used to obtain empirical data on psychological states, daily activities, and social interactions . ESM entails that participants are studied in their natural environments and that experiences are measured in a systematic and momentary way. Widely accessible smartphones offered opportunities to apply ESM on our sample. The smartphone application that we used is called “inTin” (i.e., interested in) and was developed by Akkerman and Bakker (2012–2014) for studying the development of multiple interests in all life domains and in interaction with the social network of its users. It was piloted and validated in 2015–2016 and has proven to be a reliable and valid instrument to study the idiosyncratic nature of interests in daily life, depending on proper instruction and completeness of the social network that participants add to the application .