28 Chapter 2 ABSTRACT Purpose: The Endocrine Society and the World Professional Association for Transgender Health (WPATH) published guidelines for the treatment for adolescents with gender dysphoria (GD). The guidelines recommend the use of gonadotropin-releasing hormone analogues (GnRHa) in adolescence to suppress puberty. However, in actual practice, no consensus exists whether to use these early medical interventions. The aim of this study was to explicate the considerations of proponents and opponents of puberty suppression in GD to move forward the ethical debate. Methods: Qualitative study (semi-structured interviews and open-ended questionnaires) to identify considerations of proponents and opponents of early (medical) treatment (paediatric endocrinologists, psychologists, psychiatrists, ethicists) of 17 treatment teams worldwide. Results: Seven themes give rise to different, and even opposing, views on treatment: (1) the (non-) availability of an explanatory model for GD; (2) the nature of GD (normal variation, social construct or [mental] illness); (3) the role of physiological puberty in developing gender identity; (4) the role of comorbidity; (5) possible physical or psychological effects of (refraining from) early medical interventions; (6) child competence and decision-making authority; and (7) the role of social context how GD is perceived. Strikingly, the guidelines are debated both for being too liberal and for being too limiting. Nevertheless, many treatment teams using the guidelines are exploring the possibility of lowering the current age limits. Conclusions: As long as debate remains on these seven themes and only limited long-term data are available, there will be no consensus on treatment. Therefore, more systematic interdisciplinary and (worldwide) multicentre research is required.