The first version of the Blaise System for computer-assisted data collection was released in 1986. So the year 2006 marks the 20-th birthday of the system. Although operating systems may have changed over time, and new data collection techniques may have emerged, the basic ideas and concepts of Blaise have remained the same over the years. The heart of the system, the Blaise language, has proved to be a powerful means to define data collection instruments. Designed in a time where most statistical agencies still used mainframe computers, and the first MSDOS computers came on the market, Blaise was able to keep up with rapid developments in information technology, and still plays a leading role in the world of data collection for official statistics. This paper gives an account of the 20 year long history of the Blaise System. It described why it was developed and how it evolved over time.