This study aims to explore current collaborative practices in the US, as well as investigate how the implementation varies based on districts. The sample schools were chosen through a national sample of school districts in the United States. The data was collected through a questionnaire that included multiple-choice and open-ended questions from the leaders of multilingual or EL programs. As a result, the researchers found that collaborative practices are more common in urban schools that consist of more ELs and in bigger districts that have more financial and staff resources. Furthermore, they reported that collaboration occurs more in middle school level than high school. In addition, this study confirmed the previous research reported that ESL teachers’ inequitable status and often EL designated learners are not seen as shared responsibility, which might stem from limited organizational capacity. Leaders play a critical role in creating an environment for school level professional learning and collective responsibility. Research on co-teaching is more complicated than solely focusing on the classroom, and the complexity of collaboration needs to be embraced.