Background: Sickle cell (SC) carriers have one copy of the altered gene. They are usually asymptomatic and their status mainly has reproductive implications. However, there is a small risk of clinical complications in certain situations. Although newborn screening (NBS) detects SC carriers in England, carrier testing for older children remains controversial, due to concerns it breaches children's autonomy and could result in psychosocial harm and stigmatisation. This issue is increasingly important in light of the number of children who could be identified as carriers in the future through expanded NBS or direct-to-consumer genetic testing. The impact of carrier identification on children's wellbeing is at the crux of debates about current and future NBS and testing. Four studies were undertaken to examine children's responses to being identified as a SC carrier with consideration for how professionals, parents and peers could influence adaptation.Methods: Interviews were conducted with professionals (N=25) to explore experiences of providing childhood SC carrier testing and counselling. Parents (N=29) were interviewed to examine understanding of their child's SC carrier status and experience of conveying results to children. Children of 8 parents (6-14years) participated in write-and-draw interviews. Data from each parent-child pair were analysed to explore communication about carrier status and accounts of children's understanding of, and adaptation to, their status. Focus groups (N=9) were undertaken with 69 children and adolescents (10-17 years) (not carriers) to explore understanding of carrier status, and attitudes towards peers identified as carriers.Results: Due to barriers in communication, professionals were unaware of how children adapted to their status. Few considered children's autonomous wishes or the possible harms of carrier identification in testing decisions. Parents were fearful that children would experience psychological harm or stigmatisation and this prevented, or created ambivalence about, communication of carrier results. Parents were uncertain of how children understood and adapted to carrier results. Children struggled to comprehend their carrier status and reported anxiety about the possibility they could become unwell. Children were fearful of, or had experienced, bullying. Children (non-carrier) were unaware of how carrier status was transmitted and believed it could be 'caught'. Alongside adolescents, they thought carriers might self-stigmatise and be socially stigmatised or bullied.Conclusions: Knowledge of carrier status could create psychosocial harms if children do not understand the information, which might be perpetuated by peer stigma and fail to be picked up by parents and professionals. Support mechanisms for parents, age-appropriate resources for children and education in schools are integral to facilitate family communication and improve children's understanding of carrier status. Together, these could reduce children's psychological maladjustment. Findings raise questions about the use of proxy measures to explore the psychosocial impact of childhood carrier identification.