Background: The Canadian Network for Mood and Anxiety Treatments (CANMAT) conducted a revision of the 2009 guidelines by updating the evidence and recommendations. The scope of the 2016 guidelines remains the management of major depressive disorder (MDD) in adults, with a target audience of psychiatrists and other mental health professionals., Methods: Using the question-answer format, we conducted a systematic literature search focusing on systematic reviews and meta-analyses. Evidence was graded using CANMAT-defined criteria for level of evidence. Recommendations for lines of treatment were based on the quality of evidence and clinical expert consensus. This section on "Special Populations" is the sixth of six guidelines articles., Results: Recent studies inform the treatment of MDD in children and adolescents, pregnant and breastfeeding women, women in perimenopause or menopause, and the elderly. Evidence for efficacy of treatments in these populations is more limited than for the general adult population, however, and risks of treatment in these groups are often poorly studied and reported., Conclusions: Despite the limited evidence base, extant data and clinical experience suggest that each of these special populations can benefit from the systematic application of treatment guidelines for treatment of MDD., Competing Interests: The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: GMM has been on advisory boards or a speaker for Janssen, Lilly, Lundbeck, and Pfizer. BNF has received honoraria for ad hoc speaking or advising/consulting or received research funds from Alternative Funding Plan Innovations Award, AstraZeneca, Brain & Behavioral Foundation, Bristol-Myers Squibb, Canadian Institutes of Health Research, Canadian Network for Mood and Anxiety Treatments, Canadian Psychiatric Association, Daiichi Sankyo, Eli Lilly, Hamilton Health Sciences Foundation, J. P. Bickell Foundation, Lundbeck, Lundbeck International Neuroscience Foundation, Ontario Brain Institute, OMHF, Ontario Ministry of Research and Innovation, NSERC, Pfizer, Servier, Society for Women’s Health Research, Sunovion, and the Teresa Cascioli Charitable Foundation. ZI has received honoraria for ad hoc speaking or advising/consulting or received research funds from Canadian Biomarker Integration Network for Depression, Canadian Consortium for Neurodegeneration and Aging, Canadian Institutes of Health Research, Janssen, Joan and Clifford Hatch Foundation, Katthy Taylor Chair in Vascular Dementia, Lundbeck, National Institute of Aging, Ontario AFP Innovation Fund, Otsuka, Pfizer, and Sunovion. NJ has no financial conflicts to declare. MS has no financial conflicts to declare. RJV has no financial conflicts to declare. SHK has received honoraria for ad hoc speaking or advising/consulting or received research funds from Allergan, Brain Canada, Bristol-Myers Squibb, Canadian Institutes of Health Research, Janssen, Lundbeck, Ontario Brain Institute, Pfizer, St. Jude Medical, Servier, and Sunovion. RWL has received honoraria for ad hoc speaking or advising/consulting or received research funds from Asia-Pacific Economic Cooperation, AstraZeneca, Brain Canada, Bristol-Myers Squibb, Canadian Institutes of Health Research, Canadian Depression Research and Intervention Network, Canadian Network for Mood and Anxiety Treatments, Canadian Psychiatric Association, Coast Capital Savings, Johnson & Johnson, Lundbeck, Lundbeck Institute, Medscape, Pfizer, St. Jude Medical, Takeda, University Health Network Foundation, and Vancouver Coastal Health Research Institute. RVM has received speaker and consultant honoraria or research funds from Allergan, Bristol-Myers Squibb, Canadian Institutes of Health Research, Canadian Network for Mood and Anxiety Treatments, Canadian Psychiatric Association Eli Lilly, Johnson & Johnson, Lallemand, Lundbeck, Merck, Ontario Brain Institute, Ontario Mental Health Foundation, Otsuka, Paladin, Pfizer, Queen’s University, Sunovion, Takeda, the University Health Network Foundation, and Valeant. SVP has been a consultant to Bristol Myers Squibb, Lundbeck, and Takeda; has had a research contract with Assurex; and has equity in Mensante. AVR has received speaker and consultant honoraria or research funds from Bristol-Myers Squibb, Canadian Depression Research and Intervention Network, Canadian Foundation for Innovation and the Ministry of Economic Development and Innovation, Canadian Institutes of Health Research, Grand Challenges Canada, Janssen, Lundbeck, Ontario Mental Health Foundation, Pfizer, and Sunovion., (© The Author(s) 2016.)