This paper describes an ongoing effort to build a large-scale monolingual treebank of parallel/comparable Dutch text, where nodes of syntax trees are aligned and labeled according to a small set of semantic similarity relations.Such a corpus has many potential uses and applications in e.g., multi-document summarization, question-answering and paraphrase extraction.We describe the text material, preprocessing, annotation, and alignment of sentences and syntax trees, both manual and automatic.Two new annotation tools are presented, as well as results from pilot experiments on inter-annotator agreement.On the basis of this resource, new automatic alignment software and NLP applications will be developed.