Assessment of contaminated sediments and development of remediation strategies is becoming an important priority for regulators and industries worldwide. Although sediment quality assessment frameworks exist, poor scientific procedures and a limited understanding of species sensitivity to common contaminants hinders most assessment programs. Globally, sediment quality guidelines (SQGs) for metals vary over several orders of magnitude and are not based on clear cause-effect relationships. Although equilibrium partitioning approaches to developing SQGs have been attempted, the cause-effect relationships are weak due to the many other modifying factors that influence metal bioavailability and toxicity. The inherent lack of defensible SQGs for metals currently impedes decision making processes by both regulators and industries.