As in other disciplines, Montessori teacher education is increasingly being performed online. In a five-year period at one low-residency Montessori teacher education program, 41% of adult learners did not complete their studies, exacerbating a shortage of qualified teachers. A particularly high failure rate for younger adult learners was observed. This study of a low-residency Montessori teacher education program used qualitative research to investigate how participants were affected by an increase in the amount of synchronous collaboration. The study explored how expanding collaborative opportunities affects peer relationships, social cohesion, student satisfaction, and learning outcomes. Two cohorts of teachers totaling 26 participants had weekly independent assignments replaced with small group projects and were invited to participate in optional weekly Community of Practice sessions. The results were analyzed thematically. The study drew from the literature of Social Presence (Whiteside et al., 2017) and Emerging Adulthood (Arnett, 2000) to suggest a relationship between a stage of human development and specific needs in online environments. Evidence was found that Social Presence and learning outcomes were improved for most participants. Not enough evidence was collected to determine differential effects for Emerging Adults. The study includes recommendations for designing group assignments which are both satisfactory to participants and which strengthen peer relationships. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]