Voice disorders in teachers have a significant impact on their occupational functioning and well being. Teachers are believed to have a high prevalence of voice problems because of the unfavourable acoustic environments in which they work and the high vocal demands and stress levels associated with teaching. Although the types of voice problems teachers experience should be preventable because they are caused by factors that teachers can change, there is limited information available regarding the effectiveness of different preventative strategies. Therefore, the aim of this study was to investigate the effectiveness of vocal hygiene training (VH) and vocal function exercises (VFE) in reducing vocal symptoms and vocal misuse, and increasing knowledge of voice care, maximum phonation time, and maximum phonational frequency range in school teachers. Thirty-seven teachers from four schools in Melbourne, Australia, participated in the study. Schools were randomly allocated to one of three groups: VH, VFE, and no-treatment control. The VH and VFE participants reported improved vocal characteristics and voice knowledge after training while the control group showed deterioration on most variables. The VH participants showed greater improvements than the VFE participants. These fundings indicate that preventative voice training for teachers is likely to be effective.