||This represents the first empirical inquiry into the perception of negative admission pressures (P-NAPs; e.g., perception of force or threat associated with entering treatment) among adolescents. Prior to this report, P-NAPs had only been studied within adult treatment contexts. In this study, P-NAPs was specifically investigated in relation to adolescent affective reactions when entering an outdoor behavioral healthcare (OBH; e.g., wilderness therapy) program. P-NAPs was measured via the MacArthur Perceived Negative Pressures Scale (P-NPS). Affective reactions at admission were measured via the Positive and Negative Affect Schedule - Expanded Form (PANAS-X). Bivariate regression analysis (N = 76, age range: 12-17) of a priori hypotheses demonstrated that adolescents' increased P-NAPs significantly related with (a) increased affective distress (r = .521, 𝑟!= .271, p < .001), (b) decreased affective positivity (r = -.363, 𝑟!= .132, p = .001), (c) increased affective hostility (r = .565, 𝑟!= .319, p < .001), and (d) increased affective fear (r = .359, 𝑟!= .129, p < .001). Importantly, after controlling for psychological well-being via the Youth-Outcome Questionnaire - Self-Report (Y-OQSR), hierarchal regression analyses indicated that these effects were robust: Increased PNAPs remained strongly associated with (a) increased affective distress (𝑠𝑟 = .459, 𝑠𝑟!=.211, p <. 001), (b) decreased affective positivity (sr = -.348, 𝑠𝑟!= .121, p = .002), (c) increased affective hostility (sr = .501, 𝑠𝑟!= .251, p < .001), and (d) increased affective fear (sr = .309, 𝑠𝑟!= .095, p = .005). These trends suggest that increased P-NAPs may be associated with several adverse affective reactions during the OBH admission process. In turn, P-NAPs may be linked to several other implications of adolescent treatment, including (a) adjustment into treatment, (b) treatment outcomes, and (c) willingness to seek future treatment. Future research is needed to clarify these effects, including which factors may relate to, or predict, P-NAPs (e.g., psychological well-being or parent-child dynamics). Future research can also inform adolescent treatment policy by delineating which admission procedures decrease the perception or alleviate the effects of negative admission pressures in OBH and other adolescent treatment contexts.