The recent advances in miniaturization and the creation of low-power circuits, combined with small-sized batteries have made the development of wireless sensor networks a working reality. Lately, the production of cheap CMOS cameras and microphones gave birth to what is called Wireless Multimedia Sensor Networks (WMSNs). WMSNs will boost the capabilities of current wireless sensor networks, and will fuel several novel applications. WMSNs introduce several research challenges, related to the delivery of applicationlevel Quality-of-Service (e.g., latency minimization). To address this goal in an environment with extreme resource constraints, with variable channel capacity and with requirements for multimedia in-network processing, the efficient and effective caching of multimedia data, exploiting the cooperation among sensor nodes is vital. This paper presents for the first time a cooperative caching solution particularly suitable for WMSNs. The proposed solution is evaluated extensi...