Systems and methods for enhanced runtime hosting are described. In one respect, the runtime identifies any abstraction interface(s) exposed by a host application. The abstraction interface(s) correspond to respective execution environment functionality implemented by the hosting application. During execution of runtime managed code and responsive to an action or event associated with an identified one of the respective execution environment abstractions, the runtime calls a specific interface or object corresponding to a specific one of the abstraction interface(s). This allows the host application to customize/enhance its execution environment, which includes the runtime, as a function of the implemented abstraction(s).