- ZTT stands for Zero to Three (National Center for Infants, Toddlers and Families)
- ZTT stands for Zirconium Tin Titanate (ceramics)
- ZTT stands for Zang Tuum Tumb Records (record label; UK)
- ZTT stands for Zero Transfer Time (Uninterruptible Power Supply systems)
- ZTT stands for Zinc Tolerance Test (biological research)
ZTT