Teacher shortage in the United States (U.S.) is persistent and severe and manifests more acutely in low-income school districts and mathematics and science subject areas. Strategies to recruit locally trained teachers from within the U.S. have failed to satisfy the increasing demand, and recruitment drives have extended beyond national borders to import internationally trained teachers (ITTs). While literature shows that the U.S. mathematics and science teacher workforce continues to be filled by ITTs, the problem is that little is known of their firsthand experiences of teaching mathematics and/or sciences in secondary schools in the U.S. ITTs have trained and practiced in one cultural context and immigrated to live and practice in a new cultural context. Identifying their experiences would ensure successful integration and inform recruitment and retention programs. The purpose of this generic qualitative study was to explore firsthand experiences of internationally trained teachers teaching mathematics and/or science in secondary schools in the U.S. Drawing on semi-structured interviews with 14 ITTs from diverse ethnic backgrounds and the theoretical underpinnings of social constructivism theory and expectancy violations theory, this study sought to answer the question of how ITTs describe their experiences of teaching mathematics and/or science in secondary schools in the U.S. Snowball sampling was used to select participants (n = 14), from a population of ITTs teaching mathematics and/or science in secondary schools in the U.S. The sample of nine females and five males was drawn from 13 secondary schools across four states in the Northeast and Southwest U.S. Participants received teacher training from India, Kenya, Jamaica, Cameroon, Benin, Ghana, and Nigeria. When asked to describe their experiences of teaching mathematics and/or science in secondary schools in the U.S., participants did not only describe experiences that affect their professional but also their personal lives. They also described factors that hindered or facilitated their adaptation to living and teaching in the U.S. Cultural elements permeated their descriptions. Inductive thematic data analysis yielded three broad themes: pedagogy, quality of life, and climate and culture. The themes stemmed from 11 broad categories: teacher characteristics, student characteristics, school support systems, organization structure, curriculum matters, economic upgrades, lifestyle changes, families and homes, student behaviors, school environment, and sociocultural aspects. Findings revealed the opportunities and barriers that ITTs face. Results also indicated that participants experienced professional and personal growth despite challenges. This study contributed literature to the field of ITTs' experiences in the U.S. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]