The degree of social acceptance on sexual-affective diversity directly influences LGTBI individuals’ lives. Hiding their sexual orientation or living with concerns lead to the development of internalized homophobia and, consequently, this may cause some mental health disorders. The aim was to analyze the differences between adolescents and young population in relation to their experience and concern on their sexual orientation. The sample was composed by 140 adolescents and young people (65% women and 35% men), ages ranging from 12 to 25 years old, belonging to two public secondary schools in the province of Castellón. Participants completed an ad hoc on-line questionnaire with 52 items. Three items were selected to assess participants’ experience and concern on their sexual orientation. An 1.1% of adolescents aged 12 to 18 identified as bisexual, a 3% as homosexual, a 4% had doubts and a 14% did not feel sexual attraction to any sex. Non-heterosexual people showed greater concern when discovering their orientation than heterosexual people did (45.5% vs. 3.4%). There were statistically significant differences (χ² = 40.505; p£.001). At the present moment, heterosexual maintain their concern about orientation around 3.5% differing from non-heterosexuals who obtain 31.8% (χ² = 23.838; p £.001). In spite of the differences were not significant (χ² = .404; p = .525), it was observed that non-heterosexual adolescents (12-18 years old) showed less concern than non-heterosexual young people aged 19-25 (75% vs. 61.5%). Regarding the age at which they discovered their sexual orientation, results showed that non-heterosexual participants did it later (M = 10.45; DT = 6.43) than heterosexual ones (M = 5.74; DT = 5.04). There were statistically significant differences (t = 3.84; p£.001). Finally, those non-heterosexual participants who discovered later their sexual orientation, showed more concern at present moment. These results have shown that young people and adolescents are still concerned on their own sexual orientation, especially in the cases that participants discovered a non-heterosexual one at a late age. This research emphasizes the importance of normalizing sexual-affective diversity and the need to break down hetero-normativity, so that identifying themselves as non-heterosexual individuals does not lead to any type of concern that may be the prelude to mental health disorders.