Users face many situations in which they have to disclose their data to others. In many cases, they are not properly informed about the usage of their data or the consequences of data disclosure. This book investigates how users can be supported by researching three core aspects: Firstly, problems and risks that lead to (unintended) data disclosure or arise from it have to be identified. Secondly, measures are investigated that developers can apply to mitigate these risks and meet the needs of the users. Finally, the developed solutions have to be adopted into practice. Strategies to bring security- and privacy-enhancing technologies to use are essential because a tool that is not used cannot protect anyone. The investigated scenarios are twofold: Firstly, business-to-business (B2B) collaborations, especially highlighting the perspective of owners of small and medium enterprises (SMEs) who are forced to provide data for business processes. Secondly, scenarios of everyday usage for private users that require the disclosure of data are investigated.