A daughter card for mounting to an adapter card, wherein the daughter card includes adapter card connectors for mounting to the adapter card and also an edge connector for insertion directly into a computer slot so that the daughter card may also function as a stand-alone card. The daughter card is both mechanically and electrically compliant as an independent PCI add-in card and includes a PCI edge connector for insertion directly into a PCI slot. This provides additional modularity since the daughter card can be purchased and configured as a separate and independent PCI adapter card as well as for mating to a host adapter card to provide extra functionality to the host adapter card. In addition, since the daughter card can be directly inserted into the PCI bus, the daughter card provides greater component access and probing for testing. Further, the daughter card can be tested independently of the host adapter card during manufacturing functional test, thus providing more reliable testing.