Pronoun Case is really a very simple matter. There are three cases.

1. Subjective case: pronouns used as subject.
2. Objective case: pronouns used as objects of verbs or prepositions.
3. Possessive case: pronouns which express ownership.

                                                   Pronouns that show
Pronouns as SUBJECTS       Pronouns as OBJECTS     POSSESSION

I me my (mine) you you your (yours) he him his she her her (hers) it it its we us our (ours) they

The pronouns THIS, THAT, THESE, THOSE, and WHICH do not change form.

Some problems of case:

1. In compound structures, where there are two pronouns or a noun and a pronoun, drop the other noun for a moment. Then you can see which case you want.

NOT: Bob and me travel a good deal.
(Would you say, "me travel"?)

NOT: He gave the flowers to Jane and I.
(Would you say, "he gave the flowers to I"?)

NOT: Us men like the coach.
(Would you say, "us like the coach"?)

2. In comparisons. Comparisons usually follow than or as:

He is taller than I (am tall).

This helps you as much as (it helps) me.

She is as noisy as I (am).

Comparisons are really shorthand sentences which usually omit words, such as those in the parentheses in the sentences above. If you complete the comparison in your head, you can choose the correct case for the pronoun.

NOT: He is taller than me.
(Would you say, "than me am tall"?)

3. In formal and semiformal writing:

Use the objective form after a form of the verb to be.
FORMAL: It is I.
INFORMAL: It is me.

Use whom in the objective case.
FORMAL: To whom am I talking?
INFORMAL: Who am I talking to?