Imagine getting on the tandem bike of co-teaching. You have a lot to decide. Who sits in the front and takes the lead? Who takes the backseat? The fact is, neither classroom teachers nor secondary content-area teachers have proven eager to give up leading their lesson when they have a co-teacher present, whether to support ELLs or students with disabilities. Co-teaching requires a delicate balance. Much like riding a bike, if you lean too much one way or the other, the bike will spill over. The authors, researchers in the area of co-teaching, have identified three consistent elements of successful, integrated collaborative instruction for ELLs in K12 schools: (1) trust between co-teaching partners; (2) maintenance of the entire collaborative instructional cycle, which includes co-planning, co-teaching, co-assessment of student work, and reflection; and (3) leadership support. The article highlights the importance of co-planning, a prerequisite for true co-teaching. They suggest a three-phrase framework that will help those who are new to--or overwhelmed by--co-planning.