A method for assisting a user to develop a query in a natural language includes receiving a user's query in a natural language and, while the user's query is being entered, presenting a subset of ranked query suggestions from a collection of ranked query suggestions to the user as candidates for user queries. The subset is based on that portion of the user's query already entered. The query suggestions in the subset of query suggestions are presented according to their respective rankings in the collection. Each of the query suggestions in the collection is formulated to retrieve at least one responsive instance in the knowledge base. The rankings of the query suggestions in the collection are based at least in part on stored logs of prior user sessions in which user queries were input to a search engine for retrieving responsive instances from the knowledge base.