This article is one of the fruits of the research “Maternity incarcerated from a comparative perspective” that aimed to analyse the exercise of motherhood in conditions of deprivation of liberty in a women’s prison in Portugal from experience in the Brazilian prison system. Through the ethnographic methodology- with combined techniques of participant observation, interviews, documentary analysis and projection of films with conversation groups- I carried out the field work with the woman and children incarcerated at the Mother’s House in Tires Prison. In this text, I recount methodological notes that tell my input, routes and locations in the field of research, seeking to frame them within a more general overview of prison, power arguments and positional positions in the empirical production of prison studies.