**Introduction & Rationale** Adolescence marks a time of considerable biological, social and emotional change (Due et al., 2011). Adversity during this period of life can make adolescents particularly vulnerable to mental health problems that extend into adulthood (Patel et al., 2007). However, the risk of experiencing adversity duringadolescence is not equal. Meta-analytic research indicates that sexual minorities experiences higher rates of anxiety, depression and less life satisfaction compared to heterosexuals (Semlyen et al., 2016) as well as increased emotionaldysregulation (Hatzenbuehler, McLaughlin, Nolen-Hoeksema, 2008).The reasons for this are complex and multifactorial, however the increased experience of stigmatisation due to minority status has been linked to the development of suchadverse psychological outcomes (Meyer, 2003; Hatzenbuehler, 2009). Theoretically, stigma is proposed to increase the load on general psychopathological strategies used to cope with such adversity (Meyer, 2003; Hatzenbuehler, 2009). The psychological mediation framework proposes that stressors (i.e. victimisation) increase the load on general psychopathological mediators such as rumination, suppression and negative self-schemas which in turn lead to psychopathology (Hatzenbuehler, 2009; Hatzenbuehler, McLaughlin, Nolen-Hoeksema, 2008). The internalization of stigma to one’s identity may also increase psychopathology (Coker, Austin & Schuster, 2010). The internalization of stigma can become an internal stressor, increasing the already burdened load on emotional regulation strategies via societal stigmatisation (Hatzenbuehler, 2009). This process has been labelled Internalised homophobia (also referred to as internalised homonegativtiy/heterosexism) and has gained increasing interestas a psychopathological mechanism specifc to this group (Szymanski, Kashubeck-West & Meyer, 2008). Internalised homophobia may present itself at the level of self-identity i.e. the morality of one’s sexuality, attitudes towards other sexual minorities and the willingness to disclose sexuality status due to expected stigmatisation (Nungesser, 1983). The process of Internalised homophobia is thought to elevate various mediation factors i.e. emotional regulation - suppressing feelings for the same sex, cognitive – negative self-schemas relating to morality of sexual minority status (Szymanski, Kashubeck-1 West & Meyer, 2008). Indeed, Internalised homophobia has been linked with a host of negative outcomes such as delays in sexual identity development and multiple psychosocial difculties (Szymanski, Kashubeck-West & Meyer, 2008). Specifcally, higher levels of internalised homophobia have been shown to leadto decreased wellbeing (Baams et al., 2014) , increased psychological distress (Shilo, Antebi & Mor, 2015) indirectly increased emotional dysregulation and subsequent psychological distress (Hatzenbuehler, Dovidio, Nolen-Hoeksema & Phills, 2009), and increased depressive symptoms and its impact on relationship quality (Frost & Meyer, 2009). As such, Internalised homophobia likely increases the load on psychological mediator’s (suppression, rumination, negative self-schemas) leading to psychopathology. However, there have been issues with the measurement of internalised homophobia. Earlier self-report measures assessed gay male adults specifcally and may not be valid with other sexual minority groups, these measures also suffer from content validity issues(Syzmanski et al., 2006). Another caveat of relying on explicit measures is the potential impact of social desirability effects inresponding (Greenwald , McGhee & Schwartz, 1998). The Implicit Association Task (IAT) presents a methodological advantage to dealing with these limitationsas the IAT taps into the participant’s implicit and automatic attitudes (Greenwaldet al., 1998). The methodological advantage of using the IAT to measure implicit internalised homophobia with sexual minorities has already been recognised. Hatzenbuehler et.al. (2009) used an implicit association to detect implicit preferences for heterosexual relationships over sexual minority relationships (i.e.internalised homophobia). Implicit internalised homophobia was found to be more predictive of distress than explicit measures and was mediated by suppression and rumination and its subsequent impact on psychological distress. However, Hatzenbuehler et.al.’s (2009) research was conducted on adults using a modest sample size. Research still needs to be done with sexual minorityadolescents who are a particularly vulnerable group (Coker, Austin & Schuster, 2010). Work within the UK is also lacking as research on this population is mainlyconducted in the Netherlands and US. Therefore, the aim of this study is to conduct a UK based study using an implicit association task to identify implicit internalised homophobia in sexual minority adolescents.