A keyboard for a handheld electronic device comprises ten keys arranged in four rows in a DTMF keypad format. Three of the keys respectively bearing numerals 1, 2 and 3 arranged in a first row, three of the keys respectively bearing numerals 4, 5 and 6 arranged in a second row, three of the keys respectively bearing numerals 7, 8 and 9 arranged in a third row, and a tenth key bearing a 0 located in a fourth row. The keys of the first second and third rows also bear letter characters which, either alone or in conjunction with additional letter character-bearing keys in the rows, are positioned relative to the letter characters on adjacent keys so as to form a QWERTY or Dvorak layout.