This paper summarises the results of a research project which assessed the economic impact of the public library service in the UK. Emphasis is given to a general descriptive model based on combining the diverse survey results of previous research, a survey to determine user perceptions of the value of a book loan, a model to illustrate the economic value of book buying compared to book lending in terms of the number of "reads" and estimates of the total value of the public library service to the economy New performance indicators are also proposed.