All and all of (with pronouns)
Use all of with words like us, you, it, him and her (i.e., pronouns). For normal nouns, just use all (instead of all of).

Using All and All Of

There is often confusion over all and all of. As a very general guideline, use all of when the next word is a pronoun (e.g., us, you, it, him, her).


All of us...

All of you...

All of it...  

Do not use all of for normal nouns - just use all.


All the soldiers...

All the nurses...  

I need all of the chairs.   (The word chairs is not a pronoun.)

All of the divers returned safely.

This is not a "rule" but a guideline. The word all can be an adjective (e.g., all the soldiers) or a pronoun (e.g., all of the soldiers), but as an adjective, the word all does not sit comfortably before a pronoun. Therefore, terms like "all us" sound wrong. Native English speakers would much rather hear "all of us."

For many, all soldiers seems less clumsy than all of the soldiers, but both are acceptable.

Don't eat all the cake.
Don't eat all of the cake.  

See also:

Using all right or alright
Test 'All and All of'
What are pronouns?