The increase of English language learners (ELLs) in the United States of America (USA) public school classrooms and the diversification of the global education landscape urges initial teacher preparation programs to equip mainstream teachers with appropriate skills, knowledge, and dispositions to teach ELLs. This paper reports findings from a focus group study on elementary teacher candidates' (TCs') field experiences with ELLs. Based on interviews with four groups of TCs who completed their two practicums with ELLs, the study illustrates how mainstream TCs perceive their field experiences as future teachers of ELLs. The findings suggest that TCs recognize dissonances and develop care toward ELLs through their engagements in ELL-specific field experiences. The study also demonstrates how the recognition of dissonances led to changes in TCs' beliefs and values, which was observed through their imagination. Informed by their field experiences with ELLs, TCs began forming professional agency as future teachers by imagining specific teaching strategies, methods, and approaches they would like to implement with ELLs. Implications and future directions of teacher education programs are also discussed.