Heat capacities of PrCl3and NdCl3have been measured between 0.3° and 4°K. The dominant feature of the heat capacity curves is a broad anomaly indicating a region of extensive short‐range magnetic ordering. The anomaly in NdCl3has a maximum at 0.47°K and fits closely that of a linear Ising chain model. In addition, two small peaks appear at the same temperatures as the sharp spikes found in the magnetic susceptibility. PrCl3has a sharp peak in the heat capacity at 0.4°K which is presumably associated with long‐range ordering. The broad anomaly in PrCl3has a maximum at 0.8°K. The magnetic entropy change for the temperature region of the measurements is approximately 80% ofRloge2 for both salts.