This study is an examination of the social experiences and school processes that high school immigrant students from Mexico encounter during their first year in U.S. schools and the meaning the subjects attribute to those experiences and processes in relation to their academic performance. The study is designed to answer the following research questions. How do high school age, newcomer-immigrants from Mexico characterize their first year in the American school system? How do high school age, newcomer-immigrants from Mexico perceive the social experiences and school processes they encountered during their first year in an American school? What is the role of social experiences and school processes in the academic performance of high school age, newcomer-immigrants from Mexico in their first year in an American school? Thirty high school students, ages 14-20 were interviewed in this study. Parity in gender was controlled for, selecting an equal number of females and males. Data were collected using a semi-structured interview protocol that included a variety of closed and open-ended questions with opportunities for follow-up questions to clarify meaning and add depth to responses. The interview data were analyzed using the constant comparative method in order to examine, compare, conceptualize and categorize data to derive findings. Data suggest that newcomer adolescent students from Mexico generally keep a positive perception of their first year in school. The immediate obstacles faced by newcomers in schools are unfamiliar school processes, structures, grade demotion and their inability to speak English. These obstacles impact academic performance. Positive relationships with peers, teachers and other school agents are critical for confronting and overcoming these obstacles. Additionally, relations with peers were reported to be most significant in determining the academic performance of newcomers, as peers served as academic supports, language brokers, mentors, and champions of other newcomers. Of noticeable concern, however, is that peer relationships were defined almost entirely as relationships with other newcomers, and dominated by interactions in Spanish, suggesting a degree of social and linguistic isolation at schools. Moreover, interview data suggest that only about half the participants felt like their teachers knew them, tried to know them or catered to their linguistic and or academic needs. Only a quarter of the participants reported having minimal relationships with non-teacher school employees. Data analyzed by gender suggest that females have a more positive appraisal of their first year experience than their male counterparts, report more positive relations with peers and adults on campus than their male counterparts, and have a more positive outlook on those relationships than male participants. Data also suggest an association between age and participants' perceptions of school, and the development and perceptions of relationships with peers and adults on campus. Findings for each age group in the study shows that as the participants increase in age, their perceptions of their school experience improves, the nature of their relationships with adults and peers is more positive, and their appraisal of those relationships is also more positive. Lastly, participants reported that learning English quickly, improving relations with peers and adults on campus, in addition to gaining a better understanding of school processes earlier in their experience can lead to improved academic performance.