Transgender is an inclusive term referring to people whose gender identity, expression, or behaviors are not fully aligned with that typically associated with the sex assigned at birth. As suggested by Lemma, experiencing very early rejection might lead transgender people to not feel mirrored by their parents in their early experiences of gender incongruence and this might cause problems in mentalizing. No previous studies have empirically assessed mentalization (i.e., reflective functioning; RF) in transgender people. The current study aimed to assess RF in a group of transgender people, relating RF to the attachment styles and analyzing the failure of being mirrored. Twenty-eight Adult Attachment Interviews (AAI) previously coded with regard to attachment styles were analyzed through the Reflective Functioning Scale. A qualitative analysis of the AAIs was also performed to identify different qualities of mirroring. Findings showed that most of the sample presented a low RF and that securely attachment individuals showed a higher RF. Three different qualities of mirroring emerged (suppressing, avoiding, and pretending the gender incongruity) which delineated three RF developmental trajectories, based on the security of the attachment, the ‘selectivity’ of the mirroring process, the one or both parents' mirroring abilities, and the presence of significant others.