Bioavailability is an important process that controls the uptake and, hence, the biodegradability and toxicity of organic pollutants in soils and sediments. The development of analytical tools for measuring bioavailability and/or bioaccessibility has become an important concept among contaminated land risk assessment and remediation. A considerable number of studies have investigated the use of chemical extractions as methods for determining putative bioavailability by linking extraction to a biological endpoint, such as biodegradation. The difficulty is that bioavailability is organism specific and, as such, no single chemical extraction technique has been identified with the capability to predict bioavailability as opposed to bioaccessibility. The aims of this review are (1) to introduce the concepts of bioavailability and bioaccessibility; (2) to present a brief overview of the different approaches used to predict bioaccessibility of organic contaminants in soil and sediment; and (3) to consider the role of bioavailability and bioaccessibility in risk assessment and bioremediation of contaminated land