ABSTRACT
This chapter presents my ideas for how to study individual development as a transformation process. I hope that they can be helpful to researchers planning to conduct longitudinal research. The main vehicle for outlining these ideas is a description of a longitudinal research program that I initiated and led for more than 30 years, namely Individual Development and Adaptation (IDA). It is presented in some detail, and includes the process of IDA's initiation and planning. The theoretical and empirical implications of the carrying out of the program for research on the adolescent period are discussed at the end of the chapter. Because my early experiences and educational background have been decisive for how IDA was designed and implemented, some personal information is also included.
