There is a provided apparatus for processing data, said apparatus comprising: a processor operable in a plurality modes and either a secure domain or a non-secure domain including: at least one secure mode being a mode in said secure domain; and at least one non-secure mode being a mode in said non-secure domain; wherein when said processor is executing a program in a secure mode said program has access to secure data which is not accessible when said processor is operating in a non-secure mode; said processor is responsive to one or more exception conditions for triggering exception processing using an exception handler, said processor being operable to select said exception handler from among a plurality of possible exception handlers in dependence upon whether said processor is operating is said secure domain of said non-secure domain.