The paper focuses on the advantages and challenges of comparative ethnographies of education by reconstructing the personal and professional implications of a recently completed project on the school experience of the children of immigrants in Catalonia and California, as part of a larger US-EU project that examines their social and academic integration. Team ethnography and cross-national multi-sited fieldwork, carried out in different educational settings in both countries, was complicated by the unexpected weight of a series of factors such as nationality, gender, ethnicity, language diversity, school culture and experience, academic culture and educational ideologies of a group of engaged researchers who had to make the most of them for the sake of their scientific goals, while being inevitably confronted by their subjectivities. Progressively adopting the general framework on the production of margin and center in schools, while exploring its impact on the conditions and possibilities actually available for the children of immigrants in both education systems and societies, the researchers had themselves to adjust to continuous negotiations of meaning and identity in most stages and tasks of a research process that was placing them, often individually, in vulnerable positions as observers, rather than as professional strangers in education research.