This paper presents the contribution of the Unbabel team to the WMT 2016 Shared Task on Word-Level Translation Quality Estimation. We describe our two submitted systems: (i) UNBABEL-LINEAR, a feature-rich sequential linear model with syntactic features, and (ii) UNBABEL-ENSEMBLE, a stacked combination of the linear system with three different deep neural networks, mixing feedforward, convolutional, and recurrent layers. Our systems achieved F OK 1 × F BAD 1 scores of 46.29% and 49.52%, respectively, which were the two highest scores in the challenge.