The purpose of the thesis was (a) to evaluate brief interventions for excessive alcohol consumption, and (b) to develop and evaluate a new and improved questionnaire for measuring excessive drinkers' alcohol consumption. The first two studies evaluated two computerised opportunistic brief interventions, which were aimed at reducing the alcohol consumption of excessive drinkers. The third study developed and evaluated a new alcohol consumption questionnaire called the Typical and Atypical Drinking Diary (TADD). In Study One, heavy drinking university students (n = 88) were randomly assigned to one of three groups: Computerised BriefIntervention (CBI), Computerised Brief Intervention-Enhanced (CBI-E), or a non-intervention control group. The CBI was based on the principles of motivational interviewing and was designed to motivate participants to reduce their alcohol consumption by measuring their consumption and providing them with normative feedback about their level of consumption and the consequences of it. The CBI-E included the same drinking-related components as the CBI. Additionally, however, it aimed to motivated participants to reduce their drinking indirectly, by addressing their general motivational patterns that might interfere with the emotional satisfaction that they derived from goal strivings to resolve their personal concerns. It did so by administering a computerised version of the Personal Concerns Inventory and providing participants with feedback about the results ofthe assessment. Participants (n =75) were re-assessed 12 weeks after the intervention. Males in the two intervention groups significantly reduced their average weekly alcohol consumption, unlike those in the control group. Female students significantly reduced their average weekly alcohol consumption irrespective of their group allocation. Only those participants (both males and females) who received a brief intervention significantly reduced their binge drinking. In Study Two, heavy drinking hospital patients (n = 45) were randomly assigned to three groups (as described above) and were re-assessed (n = 26) after 13 weeks. None of the three groups significantly changed their average weekly alcohol consumption; however, the two intervention groups had a nonsignificant 52% decrease in consumption, and the control group had a nonsignificant 6% increase. In Study Three, the TADD was administered to 158 university students. The measures of alcohol consumption derived from it were compared with measures from the Khavari Alcohol Test (KAT; a self-reported quantity-frequency index of drinking) and the Timeline Followback interview (TLFB; a precise but time-consuming and labour-intensive measure of consumption). Significantly more closely than the KAT drinking indices, the TADD indices approximated those derived from the TLFB. These results suggest that the simpler TADD is a good alternative to the TLFB interview. The implications ofthe results of the three studies for future research are discussed.