Each year, tobacco use is estimated to contribute to 5.4 million deaths worldwide. There is an urgent need to develop and evaluate affordable, practicable and scalable interventions to promote cessation of tobacco use. This thesis describes a pragmatic, two-arm, community-based cluster randomised controlled trial of a brief pro-active tobacco cessation intervention focused on adult tobacco users in low-income communities. First a census survey of 30,655 adults was conducted in selected administrative blocks of low income urban communities in Delhi. This assessed tobacco use prevalence and identified tobacco users eligible to take part in the randomised controlled trial. The main study was a cluster randomised controlled trial with two arms. The intervention arm was a brief intervention comprising pro-active advice to quit to all tobacco users initiated by visiting their home, advice on how to quit and a short session of training in craving reduction using simple yogic breathing exercises (BA-YBA). The control condition involved very brief advice on tobacco cessation (VBA). A total of 1,214 participants consented to take part. The primary outcome measure was self-reported abstinence for the preceding 6 months assessed 7 months after the intervention, validated by salivary cotinine concentration, with those lost to follow up considered as continuing tobacco users. The primary analysis was by logistic regression adjusting for clustering. The follow-up rate at 7 months was 95.1% and similar in the intervention and control arms. The quit rate by the primary outcome measure was 2.6 percent versus 0.5 percent in the control group (OR 5.36 CI 1.13-25.45, P=0.02). The effect size in terms of percentage point difference was similar to that found in the Cochrane review of brief interventions for smoking cessation but the odds ratio was much higher. On the basis of these findings and others in the literature, serious consideration should be given to delivery of brief tobacco cessation advice via outreach in low income communities in India.