Engineers confront an especially trying problem when they attempt to adapt their writing to unknown readers. This paper provides some practical solutions to that dilemma. The paper first identifiers four faulty assumptions often made about unknown readers — Instant Recall, Interest and Concern, Objectivity and Reason, and Mutual Vocabulary. Then the paper describes five adaptive strategies, strategies that are both alternatives to the faulty assumptions and ways of adapting to unidentified readers — Identify the Message and the Sender, Motivate the Reader, State Conclusions and Actions, Offer Necessary Background Information, and Write Carefully, Write Well. By avoiding the faulty assumptions and by implementing the suggested strategies, engineers can send forth communiques with a high degree of assurance that the messages are suited to the readers.