A method and apparatus is disclosed for providing an interlocked broadcast message that solves the problem of a system component taking action in response to a broadcast message issued by a processor before the processor receives communication that the broadcast message has been delivered. A broadcast message transaction request is issued from a processor. The broadcast message transaction request is posted in a transaction request buffer. A reply is communicated to the processor that the broadcast message transaction request has been posted, and the broadcast message is then delivered over the bus. In an alternative embodiment, after the broadcast message transaction request is issued from the processor, the broadcast message transaction request is stored in a transaction request buffer. The broadcast message is only delivered over the bus once it has been determined that the reply to the processor that the broadcast message transaction has completed can be immediately delivered to the processor following the delivery of the broadcast message.