Ownership fragmentation in multiowned housing (MOH) necessitates collective actions from homeowners for management and maintenance of the communal facilities. Yet, rationality dissuades individuals from participating in collective action which provides no positive net benefit. Rational homeowners in MOH tend to free-ride on others' efforts and, in theory, no collective action in housing management will take place. In fact, however, some homeowners of MOH do actively participate in housing management. It is thus worthwhile to examine why some are willing to participate and others are not. This study identifies determinants of homeowners' willingness to participate (WTP) in MOH management using the collective interest model (CIM). Based on the findings of a structured questionnaire survey in Hong Kong, the explanatory analyses suggest that homeowners' WTP is generally a function of beliefs about self and group efficacies, value of the collective good, and selective benefits and costs of participation, but the results are sensitive to the type of management activity. Although the existence of neither homeowners' associations nor property management agents is found to have significant impacts on homeowners' WTP, a research agenda which extends the CIM to study how the perceived efficacies of these management agencies affect WTP is proposed.