Cross-lingual automatic query annotation technique is described, for example, to classify online search queries in Arabic as being of commercial intent, without the need to use human judged Arabic queries. In examples, a query classifier available for a source language (such as English) is used to produce a query classifier for a target language (such as Arabic, German, French). In various examples, a target language query log and target language documents may be used to enable target language and target culture dependent queries to be classified. In various examples a click graph with edges weighted by click frequency is used to infer class membership of unlabeled target language queries from target language documents. In examples the target language documents may be classified using a supervised or semi-supervised classifier. In various examples the automatically labeled target language queries are used to train a target language query classifier for information retrieval and/or advertising.