Existing research shows that the activity of independent civil society organizations (CSOs) is an important ingredient of democratization and democratic consolidation. Yet, what happens when governments impose restrictions on CSO activity? This manuscript investigates how restrictions on CSOs affect the quality of horizontal accountability institutions like parliaments and courts. CSOs monitor and mobilize against violations of democratic norms. Thus, if governments impose restrictions on CSO activity, they may face fewer barriers (i.e., less scrutiny and criticism) to dismantling horizontal checks and balances. In addition, when restrictions prevent CSOs from supporting horizontal accountability institutions (e.g., with monitoring and expertise), the latter’s ability to control and constrain governments likely declines. Our large-N cross-country analysis supports this argument, suggesting that the imposition of restrictions on CSOs diminishes the quality of horizontal accountability institutions. We examine alternative explanations (i.e., prior autocratization trends and the authoritarian nature of governments) and offer qualitative evidence from Kenya and Turkey to illustrate the expected causal pathways. Our results imply that a crackdown on CSOs serves as a warning sign of deteriorating horizontal oversight.