Research in early childhood education is increasing last years. This paper wants to reflect about fieldwork and ethnography when the research is focused in children relationships under three years old. The first three years of life human beings learn to walk, to think, to talk and to relate with other; children also start to construct meanings and culture. The researchers’ aim to understand the constructions of meaning of children, or the meanings of their friendship elections and rejections, while they are acquiring language and constructing language with their peers, have a lot of limitations. The goal of this paper is doing a review about the different kinds of limitations and possibilities on ethnography with children under three years old based on the review of academic literature and the previous researches of the author with children (qualitative research conducted in two municipal kindergartens in Barcelona, Spain, and two years of participant observation).