Steganography is the science and art of avoiding the arousal of suspicion in covert communications. This paper presents a novel steganography methodology that pursues text summarization in order to hide messages. The proposed Summarization-Based Steganography (Sumstega) methodology takes advantage of recent advances in automatic summarization techniques to generate a text-cover. Sumstega does not exploit noise (errors) to embed a message nor produce a detectable noise. Instead, it pursues the variations among the outputs of autosummarization techniques to conceal data. Basically, Sumstega manipulates the parameters of automatic summarization tools, e.g. how the word frequency weights in the sentence selection, and employs other contemporary techniques such as paraphrasing, reordering, etc., to generate summary-cover that looks legitimate. The popular use of text summaries in business, science, education, news, etc., renders summary an attractive steganographic carrier and averts an adversary's suspicion. The validation results demonstrate the effectiveness of Sumstega.