"Population aging" is a worldwide occurrence facing both developed and developing countries alike. In Canada, significant public policy issues arise with the increasing number and proportion of older persons. One of the most important of these is meeting the housing needs of the more than one million older persons facing housing decisions in the next three decades. The greatest challenge to all those involved in producing, financing or managing housing for older persons is to assist the majority of older persons in their desire to remain in the community as they age. The underlying premise of this explorative study is that older persons should and must be involved at all levels of planning current and future seniors' or retirement housing. The specific purpose of the thesis is to explore "collaborative planning" as a method of involving older persons in housing issues. The rationale for the participation of older persons is developed from the review of three areas of relevant literature. In contrast to the literature on "environment and aging" and gerontology, this study seeks an understanding of the broader social, political-economic forces as prerequisite to meaningful analysis of the lower levels of the housing context. This wider perspective also forms the basis for the rationale of including older persons in the planning process. A discussion of "participation" as a process and a movement provides an introduction to two case studies as examples of "collaborative planning" involving older persons and professionals in discussing seniors' or retirement housing. The thesis research question is: What do older persons view as their housing needs and preferences, and how successful is present seniors' or retirement housing in meeting these? The structure, format and objectives of the two case studies were framed within the thesis principles and assumptions in addition to this question. The case studies were assessed for their usefulness for defining housing needs and preferences of older persons, and for examining how closely these stated needs and preferences fit existing housing alternatives. The evaluation of the case studies revealed that collaborative planning took place, and that the stated objectives of each event and those of the sponsoring organization were met. The thesis assumptions and premises were thereby substantiated. The wide impact and numerous outcomes of the case studies within the seniors' communities were also noted. However, the research question was largely unanswered in terms of "product", and the analysis includes some possible explanations. Analysis of the case studies within the broader context indicated that older persons and professionals alike are in a "reactive" mode of thinking rather than creative or "proactive" in what they visualize as seniors' housing options. Entrenched thinking and attitudes are difficult to change, and as this study concludes, education of all involved is necessary. The greater necessity is, however, the need to personalize the issue of inadequate and unsuitable seniors' or retirement housing, so that change is seen as imperative to one's own future life as an older person. / Applied Science, Faculty of / Community and Regional Planning (SCARP), School of / Graduate