Apparatus for testing semiconductor devices comprising die stacks, the apparatus comprising a substrate having an array of pockets in a surface thereof arranged to correspond to conductive elements protruding from a semiconductor device to be tested. The pockets include conductive contacts with traces extending to conductive pads, which may be configured as test pads, jumper pads, edge connects or contact pads. The substrate may comprise a semiconductor wafer or wafer segment and, if the latter, multiple segments may be received in recesses in a fixture. Testing may be effected using a probe card, a bond head carrying conductive pins, or through conductors carried by the fixture.