This paper proposes a combined model for POS tagging, dependency parsing and co-reference resolution for Bulgarian — a pro-drop Slavic language with rich mor-phosyntax. We formulate an extension of the MSTParser algorithm that allows the simultaneous handling of the three tasks in a way that makes it possible for each task to benefit from the information available to the others, and conduct a set of experi-ments against a treebank of the Bulgarian language. The results indicate that the pro-posed joint model achieves state-of-the-art performance for POS tagging task, and outperforms the current pipeline solution. 1