Results from a hermeneutic, phenomenological study, designed to increase understanding of early adolescents’ lived experiences during transition from primary to secondary school, are reported. This period is known to be stressful, among other populations, and Thai early teenagers appear to be no exception. Data were generated from 14 early adolescents, in a secondary school in southern Thailand, via interview, using the hermeneutic method to conduct and analyze interviews supplemented with field notes. Trustworthiness of findings was assured via an audit trail and rigor of the written report. Data were analyzed, based on Heidegger’s and Gadamer’s methodology. The theme, “Encountered Changes," describes Thai early adolescents’ feelings regarding transition to secondary school, including problems with emotional alteration, new and different teaching-learning approaches and facing an unfamiliar society. Three categories identified were: emotional alteration, consisting of easy annoyance, low self-confidence, being tired and bored of study, being in distress, feeling lonely among strangers and missing former friends; different learning approaches, involving encountering difficult and hard academic work, more profound content and going forward, and having to focus more on responsibility and real experiences; and, facing an unfamiliar society, including feelings of containment by strict school rules and regulations, and problems with surrounding inappropriate behavior from peers. Findings may help school health providers, parents, nurses and others better recognize and address adolescent vulnerabilities, and develop interventions that foster early adolescents’ readjustment and feelings of well-being during this important time. Keywords: early adolescence, transition from primary to secondary school, Hermeneutic phenomenological research