The present study of personal context and continuity in 23 students' thinking builds upon data from a longitudinal study of the students' conceptualisations of ecological processes. Each student was interviewed 11 times from age 9-15 about these processes. At the ages of 15 and 19, the students listened to what they said at the age of 11 and 15, respectively, and described how they thought their understanding had developed. The occurrence of charac teristic individual elements in the students' conceptions can be followed as themes in the interviews year by year. The students could, as 15- and 19-year-olds, often reveal concrete experiences from an early age that they referred to repeatedly in the interviews. Even if there was a substantial conceptual development, there was also a very strong element of personal continuity. Conceptions that had developed at an early age seemed to be important for future conceptual development.