This thesis analyses the evolution of political financing regimes (PFR) across post-communist polities from the outset of transition through the lenses of their restrictiveness. Unlike existing comparative research, that defines restrictiveness of party and campaign funding almost exclusively in terms of regulatory scope, this dissertation argues that restrictiveness emerges from the interplay between regulatory scope and intensity. While scope pertains to the gamut of financing regulations, intensity relates to their stringency. This analytical framework is then employed to assess the variation in restrictiveness along the key dimensions of PFR such as private financing, public funding, spending, transparency and enforcement. More specifically, I show that restrictiveness of regulatory provisions on each dimension does not emanate from the mere availability of various restrictions, liabilities or entitlements such as donation and spending limits, reporting and disclosure obligations, oversight and sanctioning rules or the provision of public funding. Instead, it stems from different levels of regulatory intensity, typified by how much: (i) a donor can contribute, (ii) a party or candidate can spend, (iii) public funding is provided, (iv) information is reported and disclosed, (v) autonomy and powers supervisory body holds and (vi) punishment is foreseen for financial wrongdoings. Based on this approach, I construct an original dataset of restrictiveness for 27 post-communist regimes for each regulatory dimension containing indicators that capture the nature of regulatory regimes considerably better than aggregate composite indexes. The analysis of regulatory developments reveals that despite a global shift from laissez-faire towards quite elaborate financing rules, post-communist regimes have varied significantly regarding the pace and magnitude of regulatory reform for both party statutory and election financing. Furthermore, the convergence of PFR in terms of regulatory scope was not followed by a similar process in terms of regulatory stringency. Quite the contrary, the variation in donation limits decreased neither cross-nationally nor over time, although the incentive structure of fundraising was favourable to parties and candidates, who could rely on a narrow donor base to cover their financial needs. Likewise, the gap between countries providing the most lavish and the scarcest state support to parties and candidates substantially increased once the pool of countries that introduced public funding has expanded over time. Spending caps, on the other hand, turned out to be excessively restrictive in most cases, which have clearly undermined the fairness of electoral competition and actors’ compliance by the rules. Transparency and enforcement represent the two dimensions where, regardless of the diversity of institutional configurations, post-communist regimes have resembled each other mostly. The blurry nature of reporting and disclosure provisions and the preservation of many regulatory loopholes into legal framework have allowed political parties to keep significant portions of their finances out of public scrutiny. Similarly, the control mechanism was hindered by several factors, including politicization and/or limited powers of the supervisory body accompanied by a toothless system of sanctions. Besides, by exploring the relationship between public funding with other regulatory dimensions, I found that the level of state support is unevenly correlated with their restrictiveness. While a high level of state support is not accompanied by more restrictive contribution limits, it is associated by stricter transparency and enforcement rules. Finally, the analysis shows that a more generous public funding mechanism is negatively associated with the level of political corruption and positively correlated with the proportionality of electoral system and democratisation, though in the latter case the strength of the correlation is weaker.