The aim of the study was to examine the influence of country-level cultural and political social structures on board decision making related to corporate governance practices and bank failure in Nigeria in 2009. An abductive critical realist case-study methodology, using Casual Process Tracing, inferred that cultural collectivism and unethical tribalism -probably influenced bank directors, under certain generative economic and legal conditions, to unduly interfere in board decision making related to corporate governance lapses and bank failure in 2009 in a Nigerian case-study. Furthermore, failure in the banking case-study in 2009 -within the culture of a highly collectivist Nigerian banking industry -probably triggered mechanisms of ‘financial contagion’ and ‘self-fulling prophecy’ that caused a ‘run’ on Nigerian banking stocks. The ‘run' on banking stocks revealed the full extent of under capitalisation within the Nigerian banking industry which prompted a government bail-out of one third of the private banking sector in 2009. The wider implications of this study for comparative corporate governance practice are that different national contexts, with different cultural and institutional social structures, probably warrant different national codes of corporate governance practice. Furthermore, this thesis suggests that where: 1) indices indicate high national, industry and organisational levels of cultural collectivism and 2) director impunity to reputational damage, arising from unethical conduct, persists unchecked by regulators and 3) National governments explicitly guarantee the bail-out of failing banks, then the systemic nature of bank failure experienced in Nigeria in 2009 may reoccur. To the extent that implicit agreements, to bail-out banks ‘too big to fail’ exist in the West then it may be appropriate, in accordance with this study’s typology, to also regulate behaviour in Western banking systems with both contract-based and reputation-based measures.