The response of single crystals of alpha-lead azide to moderately high electric fields has been investigated using Au contacts in a configuration that minimizes surface currents. Initiation is observed to occur at a threshold electric field of approximately 35,000 V/cm. Initiation cannot be attributed to bulk joule heating. The possibility that a space-charge-limited single carrier injection regime occurs at fields below the threshold field is assessed and tentatively rejected. Other possible mechanisms for the current voltage characteristics and for the observed field initiation are briefly discussed.