This article examines the use of information by British trade unions to react to occupational change. Using a case study of the response to welding by the Boilermakers' Society, it looks at the barriers that prevented the use of information. It then examines the rise of trade union research departments. This leads to an outline of a framework for looking at the ways in which trade unions used information, based on their attitude towards their environment. The article suggests that an “information perspective” is a useful supplement to existing ways of examining trade union history which may shed new light on their development.