Hong Kong and Macau’s legal systems were based on that of Britain and Portugal respectively before their handover to China. In 1997 and 1999 respectively, new constitutional instruments known as Basic Laws drafted and adopted by the Chinese Central Authorities came into force in Hong Kong and Macau. The texts of the two Basic Laws, both enacted to implement the Chinese project of “One Country, Two Systems”, were very similar. After the handover, courts in both jurisdictions have engaged in constitutional review and have developed some kind of proportionality analysis in evaluating the validity of legislative and administrative acts against the provisions of the Basic Law. This chapter explores the ‘visible’ and ‘invisible’ bases of constitutional judicial review in post-colonial Hong Kong and Macau. It compares the practices of such review in these two Special Administrative Regions of China, and demonstrates that the differences are largely attributable to the ‘invisible’, rather than the ‘visible’, basis of constitutional review, and that such ‘invisible’ basis is to a significant extent determined by the different legal traditions of the two former colonies, and probably to some extent also shaped by the values of and choices made by the judicial elites of the two territories.