[en] Civil Society is increasingly involved in the policy area of international arms control. Their opportunities are very limited for compliance control in the nuclear nonproliferation regime due to its particular sensitivity. The severe gaps of nuclear safeguards with respect to the capabilities to detect clandestine facilities render marginal civil society contributions highly influential and controversial. More and more data get available for the civil society that can be used to expose potential violations of the NPT. A systematic framework is presented to classify civil society contributions that allows for a systematic study. This classification uses the two parameters (a) affected safeguards stage and (b) degree of integration with the official procedures. These parameters may have the following defined values: (a) The affected safeguards stage can be i. Development and demonstration of new methodologies and technologies ii. Fact finding and data gathering iii. Sharing and publication of data and information iv. Technical analysis of data and information v. Determination of non-compliance vi. Political interpretation (b) The degree of integration can be i. Without a relation ii. Indirect connection iii. Informal interaction iv. Official contribution or mandate. A prominent example for civil society contributions is the increasing availability and capability to acquire and analyze satellite images. An emerging field is environmental sampling, analysis and related atmospheric transport simulation. These and other opportunities are put in the systematic framework to discuss their demonstrated and potential impact. In particular, possible contributions that civil society may offer for improving the detectability of unreported facilities and activities are considered with their chances and risks.