This study addresses how the policy reform concerning co-teaching in head start program in the US is enacted by actors and their interactions within the head start sites. The newly introduced co-teacher status policy in the state of Sunny in the US provides a fertile case to investigate this question. Drawing on literature on early childhood configurations for co-teaching, institutional lenses, and micro-politics, we delve into how actors creatively incorporate (or purposively neglects) the elements of the co-teaching policy into their everyday practices. Based on parallel case studies, we identify the inhibiting factors and facilitating factors in implementing co-teaching practices. This study contributes to the recent research on co-teaching within and beyond early childhood settings by demonstrating the importance of understanding the interplay of structure and agency and the perspective of micro-politics.