The thermodynamics of the Ni-Al-B system are assessed based on available literature data. Both the Ni-B and Al-B systems were revised to treat B as an interstitial element in a face-centered cubic structure, rather than as a substitutional element. In addition, the Al-B binary description was modified to account for the recent experimental work on the melting properties of AlB12. Two Ni-Al assessments are considered for the ternary assessment. For the same optimized ternary parameters, the two Ni-Al assessments produced similar results, with the differences increasing at high temperatures near the liquidus.