Rolling contact fatigue (RCF) is a pervasive and insidious problem on all types of railway systems. Although it is a dominant cause of maintenance and replacements on heavy haul rail lines, it is also a significant economic and safety challenge for commuter and metro lines. It is a subject of intense research around the globe, with strong academic research being undertaken in Europe particularly, with more practical work being performed in Australia, South Africa, and North America. The safety implications of RCF include being responsible for about 100 FRA reportable derailments annually in North America. The poster child for hazardous RCF is the Hatfield derailment in the United Kingdom, which incurred four deaths, 39 injuries, and economic fallout easily exceeding GBP1 billion, dismemberment of the railway authority and manslaughter charges against several railway officials. The economic implications of RCF to the North America railway industry for rail replacement alone amounts to over USD300 million annually, with costs of inspection and derailments, as well as damage to track and rolling stock, and derailment costs further increasing that number. Of the USD100+ million dollars spent annually on rail grinding in North America, at least ≥30 percent can be attributed to RCF. A review of the types or RCF defects on wheels and rails, causal mechanisms and monitoring and maintenance practices has been undertaken for the purpose of identifying gaps and the most pressing areas for research and development.