Survey methodology has become an increasingly popular weapon of choice in conducting research on the topic of environmental sustainability in the small firm context. However, conventional application of survey research in many empirical studies tends to ignore the inherent issues associated with the mode of administration of survey questionnaires. One of these issues is social desirability bias (SDB) arising from survey modes such as face to face, the assisted type of survey questionnaire administration and mailed or purely self-administered survey. This study is an analysis of survey data generated by two modes: purely self-administered and survey enumerator assisted. The paper argues that the presence of an enumerator in the workplace or actual site of the business to administer the survey will motivate the respondents to provide more accurate information about the firms' environmental sustainability knowledge and practices. The article offers suggestions to address SDB in carrying out surveys about environmental sustainability in small firms. Copyright © 2011 John Wiley & Sons, Ltd and ERP Environment.