In September 2013, the Association of British Bookmakers (ABB) launched its new Code for Responsible Gambling and Practice (‘the Code’). The Code included a range of measures aimed at reducing gambling-related harm and increasing business responsibility and sustainability. New measures introduced by the Code included enhanced staff training on responsible gambling with emphasis on staff interaction with customers; technological changes to machines whereby players could set limits on how long they wanted to gamble for or how much money they wanted to spend; mandatory messages on machines alerting players if they had gambled for 30 minutes or more or inserted £250 or more into the machine; greater advertising of responsible gambling messages; and enhancements of existing practice around age-verification and self-exclusion. All aspects of the Code were implemented on 1st March 2014 in bookmakers which signed up to it (termed bookmakers in ‘treated’ areas). Bookmakers in the West Midlands (termed bookmakers in ‘untreated’ areas) implemented the Code one month later, on 1st April 2014. This early impact evaluation compared machine gambling sessions in treated bookmakers in March 2014 (that is, after the Code was introduced) with sessions played in untreated bookmakers over the same period. This was to explore whether the introduction of the Code had any impact on machine gamblers’ behaviour during the first month of implementation (hence early impact). This evaluation was limited to analysis of data captured by bookmakers’ machines. Therefore, this report assesses the early impact of the Code on machine gamblers, rather than all gamblers within bookmakers. Accordingly, more attention is given to the new machine tools (voluntary limits and mandatory alerts).