Many influential style guides endorse the stylistic prescription that writers, particularly technical writers, should revise noun compounds into phrasal or clausal paraphrases. While the prescription is well-intentioned, it fails to take into account that a reader's comprehension of compounds, whether long or short, is a complex process dependent upon that reader's prior knowledge. In addition, the prescription ignores the fact that what retards one reader's comprehension of a compound may not retard--and might even facilitate--the comprehension of another. Therefore, in making their decisions about whether to use or revise noun compounds, writers must consider the intended reader. To help in this effort, they should apply four tests that order the decision criteria into a heuristic. Applied in order, the tests require the writer to determine if a compound (1) falls within a intended reader's general, technical, or idiomatic knowledge; (2) functions as a common, easily understood way of expressing an idea; (3) presents ideas efficiently; and (4) is stylistically efficacious. If the compound survives all four tests, it should remain intact; if it fails even one, it should be revised. The four tests form the basis of a theory of prescriptive style, but not a theory of comprehension. Theories of how readers understand noun compounds can lead writers to produce even more specific heuristics for using and revising them. (FL)