Key findings

• The way in which the content of a brief online alcohol intervention was presented to users impacted on levels of engagement with the intervention.
• Users who viewed a tunnelled version of the online intervention (in which the content was presented in a pre-determined order) viewed more pages and spent more time on the website than participants who viewed a free-roam version (in which they could view the content in any order).
• Increasing and higher risk drinkers were more likely to make a plan to cut down on their drinking in the tunnelled versus free-roam version of the intervention.
• The intervention led to significant reductions in alcohol consumption at one- and six-month follow-up.
• The structure of the intervention (tunnelled versus free-roam) had no impact on the effectiveness of the intervention in reducing alcohol consumption.
• Instructing increasing and higher risk drinkers to make if-then plans linking high-risk situations with appropriate behavioural responses was no more effective in reducing alcohol consumption than instructing them to choose strategies to cut down on their drinking.