The marketing discipline is repeatedly criticized for overreliance on a small set of quantitative methods which has the potential to delimit the scope of inquiries and introduce inherent method bias that undermines the trustworthiness of findings. The purpose of this research is to investigate the level of methods diversity in marketing research and to consider the impact of methods diversity on the marketing discipline. To accomplish these objectives, this study reports the results of an extensive content analysis of articles published in five leading marketing journals over a 20-year period (1990–2009): Journal of the Academy of Marketing Science, Journal of Consumer Research, Journal of Marketing, Journal of Marketing Research, and Marketing Science. Results reveal a disturbing downward trend in methods diversity resulting from increasing reliance on two methods, experiments and modeling.