In this chapter first of all I will highlight peculiarities of the GTM within qualitative approaches to investigate teachers’ practices by providing examples of some research I have conducted in schools during the last years throughout this approach. These examples should emphasize the type of research questions that can be addressed by GTM and in which situations it is more suitable for the study of teaching practices. Then, I will question some theoretical issues focusing on the very nature of the theory in GTM, defined as “processual”, able to explain a set of phenomena by highlighting their logical-temporal sequences. Then, to support my argument about the opportunities and the conditions for using GTM in exploring teachers’ practices, I will underline the characteristics of a theory grounded: relevance and practitioner’s usefulness. In doing so I also address one of the major criticisms against this methodology: the relationship with pre-existing theories. Finally I will spend a few words about technical features of the method such as sampling and above all coding procedures, by illustrating procedures with examples taken from my own research.