When Will Baby Understand "No"?

Actually babies start understand the meaning of “No” as young as 6 months old, but they will still do whatever they are about to do. Only when they are 12 to 18 months will they start to obey you when you say “No”.

During that time they probably already know how to walk, so you have to make sure your house is safe enough for your baby to reduce the use of the “No” word. If you feel that you use too much “No” in a day, you can alternate with other words such as “Yucky” or you can use non verbal signs like moving your finger or hand. They will understand the meaning of “No” and learn to obey you if you are consistent.