Twistor theory is a rapidly developing field with numerous applications to geometric analysis, general relativity, and mathematical physics. This work compiles approximately 70 Twistor Newsletter articles written and distributed informally over the past 20 years. The articles cover the various branches of twistor theory and contain announcements and descriptions of major developments, statements of current problems, and tentative proposals for their solution. Much of the material is unavailable in the official literature. This compilation makes the material available to a general audience in an accessible form.