MSSA

MSSA may refer to:


 * Member of the Order of the Star of South Africa
 * Methicillin-sensitive Staphylococcus aureus, a subspecies of bacterium
 * Military Selective Service Act, a law establishing the current Selective Service System in the United States
 * Military-style semi-automatic, a firearm (abbreviation commonly used in New Zealand)
 * Mind Sports South Africa
 * Montreal Student Space Associations
 * MSSA Chemical company, a French chemical company, also known as Métaux Spéciaux
 * Master of Science in Social Administration, master's degree from the Mandel School at Case Western Reserve University, equivalent to a master of social work
 * Multi-channel/-variate Singular spectrum analysis, an extension of the SSA technique