Democratic consolidation is the process by which a new democracy matures, in a way that means it is unlikely to revert to authoritarianism without an external shock. The notion is contested because it is not clear that there is anything substantive that happens to new democracies which secures their continuation beyond those factors that simply make it 'more likely' that they continue as democracies. Unconsolidated democracies suffer from formalized but intermittent elections and clientelism. 
Some scholars think that the process by which a democracy becomes consolidated involves the creation and improvement of secondary institutions of the democracy. Linz and Stepan's thesis, for example, is that democracy is consolidated by the presence of the institutions supporting and surrounding elections (for example the rule of law).
O'Donnell believes that the institutionalization of electoral rules is not the most interesting feature of democratic consolidation. His approach is to compare the formal institutional rules (for example the constitution) with the informal practices of actors. Consolidation on this view is when the actors in a system follow (have informally institutionalised) the formal rules of the democratic institution.
Almond and Verba are the originators of this theory. It locates the consolidation of democracy with the values and attitudes which emerge with, and work to sustain, participatory democratic institutions relate to the manner in which people within a polity view their relationships with others vis a vis their own interests.
Putnam believes that political capital needs to be accrued to consolidate a democracy.
Fukuyama claims that the key to consolidation is political culture.
One of the suggested causes of non-democratic consolidation is brain drain in which high skilled workers from developing countries migrate to high-income and capital-rich countries. This leaves many new democracies in the developing world problems in terms of steering effective governance due to the lack of high-skilled professionals. (for example: Regilme, 2013)
- O'Donnell 1996 'Illusions about Consolidation'
- Linz and Consolidated Democracies'
Regilme Jr, Salvador Santino F. "Is International Labor Migration Good for Democratic Consolidation?." Peace Review 25.1 (2013): 97-103.