Background Families whose child has unexplained intellectual or developmental differences often hope that a genetic diagnosis will lower barriers to community-based therapeutic and support services. However, there is little known about efforts to mobilize genetic information outside the clinic or how socioeconomic disadvantage shapes and constrains outcomes.Methods We conducted an ethnographic study with predominantly socioeconomically disadvantaged families enrolled in a multi-year genomics research study, including clinic observations and in-depth interviews in English and Spanish at multiple time points. Coding and thematic (...) development were used to collaboratively interpret fieldnotes and transcripts.Results Thirty-two families participated. Themes included familial expectations that a genetic diagnosis could be translated into information, understanding, and assistance to improve the quality of a child’s day-to-day life. After sequencing, however, genetic information was not readily converted into improved access to services beyond the clinic, with families often struggling to use a genetic diagnosis to advocate for their child.Conclusion Families’ ability to use a genetic diagnosis as an effective advocacy tool beyond the clinic was limited by the knowledge and resources available to them, and by the eligibility criteria used by therapeutic service providers’ – which focused on clinical diagnosis and functional criteria more than etiologic information. All families undertaking genomic testing, particularly those who are disadvantaged, need additional support to understand the limits and potential benefits of genetic information beyond the clinic. (shrink)