This paper focuses on the importance and the effectiveness of various types of informal support for older persons’ psychological well-being. It examines the effects of objective measures of informal support (such as size of social networks and frequency of contact) and subjective measures (such as satisfaction with the support received) on psychological well-being of older occupants in different household circumstances (i.e.,living alone, with spouse or relatives, in old urban areas or new towns, in private or public housing). Data were collected from face-to-face interviews with a sample of 518 older persons (224 males, 294 females) aged 60 and over, systematically drawn from a GIS-derived framework of housing districts in old urban areas and new towns in Hong Kong. The results show that both objective and subjective measures of informal support were related to older persons’ psychological well-being, but subjective measures of informal support (specifically satisfaction with support received from family members) were found to be more important predictors of psychological well-being. Furthermore, the effects of size of social network on psychological well-being were stronger for older persons who lived alone than for those who lived with a spouse or relatives. The results also show that persons who lived in the old urban areas received more support than did their counterparts in the new towns and older persons who lived in public housing received more objective informal support than those who lived in private housing. The implications of the findings for policy towards older persons in Hong Kong and similar Asia-Pacific societies are discussed.