This dissertation in practice explores the intersection of computer science education, specifically computational thinking and programming, with mathematics achievement among 15- year-old students in selected English-speaking countries. The research addresses a gap in understanding whether skills developed through computer science can positively influence mathematics performance by assessing the extent to which learning in computer science transfers to mathematics. To achieve this, a quantitative methodology was employed, incorporating pilot study data from a single school and large-scale survey data from the Programme for International Student Assessment (PISA) 2022. The analysis assessed the correlation between regular participation in programming activities and mathematics attainment, controlling for covariates such as gender, mathematics anxiety, growth mindset, socio-economic status, immigrant status, and reading ability. Key findings reveal that programming's impact on mathematics performance is context-dependent. In New Zealand, students who regularly engaged in programming significantly outperformed their peers in mathematics, particularly in higher-order thinking, problem-solving, and spatial reasoning -- indicating evidence of near transfer. However, in countries like Canada, Ireland, and the United Kingdom, the effect was negligible or non-significant, suggesting that programming's influence is not uniform across contexts. Additionally, mathematics anxiety, socio-economic status, gender, and reading ability emerged as significant predictors of mathematics performance across all countries, highlighting the multifaceted nature of mathematical achievement. Results from this study suggest that integrating computer programming into the curriculum can enhance mathematics learning when programming activities are intentionally aligned with mathematical objectives. Cross-disciplinary teaching, intertwining computer programming and mathematics shows promise in boosting outcomes. However, the effectiveness of such integration depends on contextual factors like curriculum design and instructional quality. A well-structured curriculum and teaching methods that promote skill transfer are key to increasing both the likelihood and the benefits of successful transfer. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]