The widespread dissemination of IEEE 802.11 networks and the enhancement of positioning techniques based on RF signal strength (e.g., sensors, positioning triangulation algorithms, etc) have fostered the development of location-based and context-aware services and applications. These applications offer several benefits to the end-users, e.g. adaptation to the device and wireless network limitations, access to location- specific information, or the ability to send location-specific notifications to other users (e.g., Geocaching). However, there are two main challenges concerning the development and use of context-aware applications: the complexity in developing context provisioning services and the need to guarantee the privacy of the users' context information (e.g., their location). In order to support the development of context-aware applications, we have designed and implemented some services that constitute the core of a context provisioning architecture called MoCA (Mobile Collaboration Architecture). These services implement the gathering, processing and diffusion of context information through synchronous and event-based communication interfaces. MoCA architecture has been used as a basis to the development of our research about privacy in which we have designed a service that aids the end-user in defining the privacy level for his/her contextual information, and in particular for his/her location information. As part of our work, we define the conceptual model underlying our privacy control service (targeted at a community of users) and discuss the most important requirements that should be conside- red in the design of such a service. Most of these requirements have guided the design and implementation of the Context Privacy Service (CoPS). This service has been integrated to the context provisioning services of the MoCA middleware.