We introduce an efficient text input technique that can be used in various environments where conventional full-sized keyboards cannot be used. The technique, called POBox, consists of two steps for entering a word or a phrase. First, a user enters a small part of the word or some other attribute, and POBox dynamically searches a dictionary for candidate words and shows them to the user for selection. The user then selects the desired word from the candidate list, and POBox enters the word into the user’s document. POBox uses the context of the user’s document to help identify likely candidates. Many times POBox can predict the desired word based on the context. This allows the user to skip the first step and enter text even more efficiently. We show that the same technique can be applied to various handheld and ubiquitous computers including PDAs and cellular phones, where conventional full-sized keyboards are inadequate.