The aging population is one of the demographic changes in the 21st century. World Health Organization defines an age-friendly city as a place that has an “inclusive and accessible urban environment that promotes active aging.” It receives considerable attention in the field of gerontology and contains important aspects of sustainable urban development. Unfortunately, there have not much research that addresses the relationship between aging-friendly and sustainability. There is a need to modify the market mechanism to achieve environmental objectives while striking a balance between social and economic considerations. This paper aims to empirically examine the integrated relationships between the dense urban environment and the social and emotional needs of the elderly in the Hong Kong context. The on-street survey was conducted in eight districts in Hong Kong to collect the opinions about aging-friendly criteria and sustainability indicators. It utilizes principal component analysis and multiple regression technique to unveil the mask of their intrinsic relationship. The empirical results suggest how the aging-friendly factors have impacted the economic, environmental, and social sustainability to a certain extent. Notably, two key findings were revealed from the empirical results. (a) “Outdoor Spaces” is consistently found not to be a planning factor that can enhance three types of sustainability, irrespective of the age groups in Hong Kong; (b) “Community Support and Health Services” is regarded as a significant factor, with the exception of economic sustainability (age group ≤60).

Attempts for implementing sustainable urbanization have been reported and documented around the world. These efforts have led to a vast number of exemplary sustainable urbanization practices, classified as best practices. Best practices contain valuable information in the form of experiences, and learning from them represents an opportunity to replicate successful practices in other cities. This study collected and analyzed 185 best practices in sustainable urbanization from around the world. The main areas of action, the key methods adopted and the outcomes achieved by these practices were identified. Key elements in successful sustainable urbanization strategies were found by conducting a series of association analyses between the areas of action, methods and outcomes. Findings highlight the importance of community participation, capacity building, education, partnerships and job creation in achieving urban sustainability.