Senegal:
18 years of age; universal
Seychelles:
17 years of age; universal
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