Purpose: The purpose of this study was to better understand how lesson study (LS) impacts the pedagogy and attitudes of teachers in varied sociocultural contexts. The authors investigated responses of teachers in Kenya and the USA who were new to LS. Design/methodology/approach: Teacher interviews after LS were qualitatively and inductively analyzed with Teacher Education and Development Study: Learning to Teach Mathematics as a conceptual/analytical framework. Findings: Results varied between Kenyan and US teachers. Kenyan teachers reported increases in content and pedagogical content knowledge. They suggested participating in LS was an enjoyable, productive struggle and emphasized the value of planning for lessons and the role of the outside expert. US teachers described consideration of students' needs, abilities, and learning strategies. They described LS as a positive experience, even though making time for the process was challenging. Procedurally, US teachers valued research and collaboration. Although both the process and responses differed, US and Kenyan teachers' reflections highlight affordances of LS. Research limitations/implications: This study is a small-scale, comparative case study. Future research could ask similar research questions in other contexts and with greater numbers of participants. Practical implications: Views of teaching and learning and typical structures for teachers' professional learning vary by context; these factors should be considered when planning and implementing LS. Originality/value: The study responds to an identified need to learn more about how LS contributes to teachers' different views of teaching and learning, which are embedded in various sociocultural settings.