Over the last two decades the incidence of overweight and obesity among children and adolescents has reached epidemic proportions in both developed and developing nations. Reducing the incidence of childhood overweight and obesity is of particular importance in countries undergoing social and cultural transitions, such as Trinidad and Tobago, where chronic diseases, such as childhood obesity may have severe social and economic impacts on public health. Although there are a number of studies that have investigated the health and lifestyle behaviours of school aged children, very little information exists about health and lifestyle behaviours of school age children in Trinidad and Tobago. Also, little information exists on the development of questionnaires to address health related issues within this culture and age group. The purpose of this study was to describe the development and pre-test of a knowledge, attitude, belief and practice (KABP) questionnaire to assess healthy lifestyle outcomes of school aged children in Trinidad and Tobago. Three data sources were used for the design and pre-testing of the questionnaire: content analysis of the literature, interview of key stakeholders, and onsite observations. An in-depth review of the literature was conducted for insights about questionnaire development. Interviews (individual and focus groups) were conducted of key stakeholder groups (school staff, the national school feeding program and curriculum officers) and children to determine current policies and practices, beliefs, barriers, and attitudes towards promoting health lifestyles (nutrition and fitness) in Trinidad and Tobago’s elementary schools. Site observations provided insight into the school food environment, class room practices, and food services offered at school. Observations were recorded using field notes and interviews were tape recorded and transcribed verbatim. Interview data from each participant was analyzed separately for dominant themes and recurring topics. The interviews were then compiled to establish the main issues which the questionnaire needed to address. The KABP questionnaire addressed general knowledge about healthy eating and activity, screen time, physical activity, snack and food choices, and self efficacy. The KABP questionnaire consisted of question items that were developed to fit the issues unique to Trinidad and Tobago, and items from previously validated questionnaires which were modified to fit the context of Trinidad and Tobago. The questionnaire was then pre-tested with a sample group of the target population. Pre-testing was done one-on one, in small groups and in the classroom setting. Based on pre-test results the questionnaire was then modified to form version 1.0 of the KABP questionnaire. Version 1.0 of the KABP questionnaire consisted of 30 questions divided into four categories. This culturally sensitive age appropriate questionnaire was the foundation of the KABP questionnaire which was used to collect baseline, midpoint and endpoint of the larger project