School-based interventions involving teacher training programmes have been shown to benefit teachers' ability to identify and manage child mental health problems in developed countries. However, very few studies have been conducted in low-income countries with limited specialist services. The aim of the study was to evaluate the impact of the training programme on teachers' knowledge and awareness. A total of 114 primary school teachers from five schools in Karachi participated in a two-day (10-12 hours) workshop to provide them with an understanding of common child mental health problems and train them in basic skills. Their pre-and post-training knowledge was evaluated through a rating scale and open-ended questions. Single tailed "t"-test, involving paired differences, was applied for participants' scores. Pre-/post-training differences were statistically significant. The training sessions were associated with an improvement in teachers' knowledge and awareness of various signs and symptoms of common child mental health problems. The greatest improvement was noted in response to strategies of managing difficult behaviours, as 61% of respondents were able to formulate appropriate behavioural management techniques after the training. In low-income developing countries like Pakistan, teachers should be trained in early-intervention programmes for the identification and school-based management of less complex emotional and behavioural problems. Such interventions can maximise the use of sparse mental health resources.