This article describes a US initiative to provide intelligence to Iran in 1979, as radical Islamists were becoming increasingly powerful there and tensions were escalating with the United States. This initiative began in May 1979, when Prime Minister Mehdi Bazargan and other Iranian officials asked US embassy personnel for information on ethnically based uprisings that threatened the new Islamic regime. It culminated when a CIA officer gave two briefings in mid-October warning Iran’s leaders that Iraq was making preparations for a possible invasion of Iran. It ended abruptly in November 1979, when radical Islamist students seized the US embassy in Tehran. Iran’s leaders did not heed the US warning and were entirely unprepared for the Iraqi invasion of September 1980, which had a devastating impact.