A system is disclosed that includes components and features for enabling enterprise users to securely access enterprise resources (documents, data, application servers, etc.) using their mobile devices. An enterprise can use some or all components of the system to, for example, securely but flexibly implement a BYOD (bring your own device) policy in which users can run both personal applications and secure enterprise applications on their mobile devices. The system may, for example, implement policies for controlling mobile device accesses to enterprise resources based on device attributes (e.g., what mobile applications are installed), user attributes (e.g., the user's position or department), behavioral attributes, and other criteria. Client-side code installed on the mobile devices may further enhance security by, for example, creating a secure container for locally storing enterprise data, creating a secure execution environment for running enterprise applications, and/or creating secure application tunnels for communicating with the enterprise system.