Abstract: We study the design of split keyboards for fast text entry with two thumbs on mobile touchscreen devices. The layout of KALQ was determined through first studying how users should grip a device with two hands. We then assigned letters to keys computationally, using a model of two-thumb tapping. KALQ minimizes thumb travel distance and maximizes alternation between thumbs. An error-correction algorithm was added to help address linguistic and motor errors. Users reached a rate of 37 words per minute (with a 5% error rate) after a training program.