The capability to gather and timely deliver any relevant information useful in service-provisioning environments, typically called context data, is increasingly recognized as a core function of modern ubiquitous and mobile systems. However, notwithstanding the large amount of literature on context modeling and representation, much work is to be done in obtaining context data distribution and retrieval with guaranteed quality levels. This paper offers three main contributions along that direction. First, it proposes a simple way to specify context data distribution requirements: these objectives called context data distribution level agreement (CDDLA) focus mainly differentiated priorities, quality metrics, and delivery delay. Second, it presents how to translate CDDLA into a set of system-level parameters to drive the infrastructure configuration. Third, it describes our novel infrastructure for quality-aware context data distribution in mobile and wireless wide-area environments. The paper reports some experimental results to point out how our solution can grant context data dissemination with required quality, while achieving overall system scalability.