Despite interest in meaningful citizen participation and in cooperation with community organizations in planning, local governments generally work haltingly, sporadically, and often ineffectually with neighbourhoods and neighbourhood organizations. Little previous work has examined the factors which affect the adoption of power-sharing decision-making models or structures between neighbourhood or community organizations and local governments. A selected literature review suggests participation is important to functioning democratically in representative systems, and that power-sharing forms of citizen participation are most meaningful. It situates neighbourhoods and neighbourhood organizations as units capable of enhancing democratic functioning, i f properly resourced and supported. This thesis collected data from a review of documents and from fourteen interviews with key informants involved with the introduction of a power-sharing policy on neighbourhood planning in Seattle, Washington. The findings indicate that in Seattles case, four factors combined to lead to the policys adoption: (1) the presence of functional neighbourhood organizations, (2) a conducive local political context, (3) application of pressure, and (4) inclusion of elements in the policy addressing political needs and the quality planning imperatives of inclusiveness and balance. These findings suggest that cities benefit when community (of many kinds) is fostered, a conducive context is created, neighbourhood and community groups apply pressure effectively, and planning policy is devised which engenders both inclusiveness and realism. A discussion of the significance and six suggestions for further research close the thesis.