Methods for supporting grid frequency stabilization using widespread flexible load and DER are becoming essential as the portion of synchronous generation decreases. This article develops a framework for providing fast primary frequency response that leverages deferrable loads and DER coordinated using high-speed measurements in real time to ensure that local objectives are met. The framework is demonstrated in a residential-scale experiment with four household appliances and an inverter. The effectiveness of an example load management algorithm is demonstrated using three underfrequency anomaly test cases. The experimental data corroborates that in all cases, the entire coordinated response, from detection and measurement of a frequency anomaly to completed coordinated net-load response, is completed within 143 ms (~8.5 cycles).