In the scientific study of dreams, as in the scientific study of any other topic, it is important to first clearly define the phenomenon one is investigating. The definition determines what exactly is being studied. Then, the methods for collecting and analyzing data regarding this phenomenon need to be chosen. These methods determine what kind of results are obtained, to what extent the results reflect the phenomenon of interest, and whether the results can be trusted. This chapter gives an overview of how dream experiences are scientifically studied: how dreams and dreaming are defined, what kinds of methods are used to collect and analyze dream data, and what aspects need to be considered when conducting and reading studies that investigate dream experiences (see also Kahan & Horton, 2012, and Zadra & Domhoff, 2017).