Sierra Leone
18 years of age; universal
Singapore
21 years of age; universal and compulsory
Slovakia
18 years of age; universal
Slovenia
18 years of age; universal (16 years of age, if employed)
Solomon Islands
21 years of age; universal
Somalia
18 years of age; universal
South Africa
18 years of age; universal
Spain
18 years of age; universal
Sri Lanka
18 years of age; universal
Sudan
17 years of age; universal, but noncompulsory