Many organizations seek or need to produce documents that are written plainly. In the United States, the Plain Writing Act of 2010'' requires that many federal agencies' documents for the public are written in plain English. In particular, the government's Plain Language Action and Information Network (PLAIN'') recommends that writers use short sentences and everyday words, as does the Securities and Exchange Commission's Plain English Rule.'' Since the 1970s, American plain language advocates have moved away from readability measures and favored usability testing and document design considerations. But in this paper we use quantitative measures of sentence length and word difficulty that (1) reveal stylistic variation among PLAIN's exemplars of plain writing, and (2) help us position PLAIN's exemplars relative to documents written in other kinds of accessible English (e.g., The New York Times, Voice of America Special English, and Wikipedia) and one academic document likely to be perceived as difficult. Uncombined measures for sentences and vocabulary---left separate, unlike in traditional readability formulas---can complement usability testing and document design considerations, and advance knowledge about different types of plainer English.