Behaviors are generated from complex interactions among networks of neurons. Single-unit ensemble recording has been used to identify multiple neurons in functioning networks. These recordings have provided insight into interactions among neurons in local and distributed circuits. Recorded units in these ensembles have been classed based on waveform type, firing pattern, and physical location. To identify individual projection neurons in a cortical network, we have paired tetrode recording with antidromic stimulation. We developed techniques that enable antidromic identification of single units and study of functional interactions between these neurons and other circuit elements. These methods have been developed in the zebra finch and should be applicable, with potential modifications that we discuss here, to any neural circuit with defined subpopulations based on projection target. This methodology will enable elucidation of the functional roles of single identified neurons in complex vertebrate circuits.