In 2014, the American Montessori Society (AMS) School Accreditation Commission, with the support of the AMS Board of Directors, reaffirmed the importance of 3-year multiage classrooms, making that 3-year range the standard for accreditation for Montessori Early Childhood, Lower Elementary, and Upper Elementary programs (American Montessori Society, 2014). Still, there are many schools that struggle with where to best "place" their tweens, the sixth-grade students, who are usually 11 when they start sixth grade and turn 12 over the school year. The question is, Are they best served in Upper Elementary or Middle School classrooms? It is the authors' belief that a student's sixth-grade year in a Montessori program should be in an Upper Elementary classroom. Experiencing the mastery and leadership possibilities of the final year in the 3-year cycle of Upper Elementary is a significant opportunity for children to consolidate strengths they have developed. Being "known" (by teachers and peer groups) and feeling safe and challenged helps these young people in the construction of their strongest selves. In their communities and within the framework of the broad and deep Montessori curriculum, students practice effective self-expression based on self-awareness and appreciation for their own individual gifts and quirks. This healthy experience of personal power is a great solidifier of the self and a bolster for facing the challenges of the next plane of development. Why do so many Montessori programs "lose" their sixth-graders, then? In discussions with Upper Elementary teachers and school administrators, the authors found common scenarios which are shared in this article.