This investigation was a confidential case study that explored the qualities of the mathematics program in a Catholic all-girls academic high school, also known as an academy, and how those qualities changed over time. National interest in students' persistence and achievement in mathematics and the national priority of equitable opportunity for all students to be successful in mathematics support the need for this study. Catholic academies were part of the alternative paradigms of Catholic and of single-sex schooling that were studied and debated in educational and political circles during the latter 20th century as possible models for improving student achievement in American public education. Although such schools have been embedded in large-scale and qualitative research studies, Catholic all-girls high schools have been underrepresented in studies of learning communities in mathematics education within sociocultural research. Through the qualitative methodology of portraiture, past and current mathematics teachers and alumnae shared their perceptions of teaching and learning mathematics. Learning experiences inside and outside the classroom affected students' persistence, engagement, and self-efficacy regarding mathematics. Semi-structured interviews with ten mathematics teachers and eleven mathematically successful alumnae formed a portrait of learning that was focused, rigorous, and respectful. More than 1,400 alumnae responses to an online survey that explored their high school mathematics experiences and the impact on their mathematical lives further shaped the portrait by quantifying high engagement and lifelong confidence, regardless of socio-economic status. Further evidence was gathered through the examination of school, congregational, diocesan, and state education artifacts to corroborate perceptions. The school's mission of "the More," which reflected its sponsoring congregation's Jesuit roots, was realized within the mathematics program through high expectations and expanded opportunities for students to experience mathematics in deep and varied ways. Strong teacher content knowledge and supportive, problem-solving pedagogy elicited continued student persistence and engagement. Weak pedagogies that utilized memorization and were exclusionary negatively impacted student learning and self-efficacy. Findings suggest topics for further research within mathematics education as well as other social science fields. [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.]