This study relied on sociocultural understanding of teacher learning, which highlights how teacher candidates construct their own learning and adjust or extend their instructional values, priorities, and beliefs within their teaching contexts (Johnson, 2009). It used activity theory as a conceptual framework (Engeström, 1999) and explored how teaching practicum experiences contributed to 5 ESOL teacher candidates' learning in a 13-month intensive MA TESOL program. Findings from the study illustrate that the teaching practicum made significant contributions to ESOL teacher candidates' learning to teach in the program. Through the teaching practicum, teacher candidates (a) learned how to navigate in the school context, (b) learned about the nature of establishing relationships with the other members of the teaching community, (c) used the mediating artifacts with the support of mentors and supervisors, (d) found opportunities for constructing a mutually informative and dialogical relationship between theory and practice, and (e) gained closer understanding of ELLs.