The Special Safeguard Mechanism (SSM) was a key issue in the July 2008 failure to reach agreement in the WTO negotiations under the Doha Development Agenda. It includes both price (P-SSM) and quantity-triggered measures (Q-SSM). This paper uses a stochastic simulation model of the world wheat market to investigate the effects of policy makers implementing policies based on the SSM rules. Implementation of the Q-SSM is found to reduce imports, raise domestic prices, and boost mean domestic production in the SSM regions. Rather than insulating countries that use it from price volatility, it would actually increase domestic price volatility in developing countries, largely by restricting imports when domestic output is low and prices high. We estimate that implementation of the Q-SSM would shrink average wheat imports by nearly 50% in some regions, with world wheat trade falling by 4.7%. The P-SSM has only small impacts on the mean or variability of import prices into developing countries but increases the instability of producer prices in seven of nine developing regions by triggering duties against exports to partner countries. The results highlight the importance of setting import policies in line with policy goals, rather than by following the SSM rules.