The future wireless mobile devices considered in this paper incorporate three key features: (1) Wireless Wide Area Network (WWAN) radios, (2) short-range high-data-rate Wireless Personal Area Network (WPAN) radios, and (3) large (>100GB) amounts of on-board cache. Approaches for finding and exploiting knowledge of Social Networks to decrease spectrum congestion and network latency in networks employing such dual-mode wireless mobile devices, including special policies for users such as emergency responders, are presented. Example scenarios indicate that significant improvements in overall quality of service quality can be achieved when wireless network service providers exploit knowledge of social networks to guide on-device caching on such networks. Analyses based on realistic scenarios indicate that the proposed approach has the potential to (1) avoid blocking of key users during an emergency, (2) decrease average wireless network latency by up to 5X, and (3) decrease spectrum congestion by up to 1.3X.