The English language is confusing and contradictory. Pronouns are no exception. Pronouns are those words that take the place of a noun – I, he, it, they, etc. What gets confusing is when to use which one. Many of us have been so conditioned to hear (and thus, say) “Jacob and I,” that we now think it’s ALWAYS so-and-so and I, but that certainly isn’t the case. Like most grammar rules, it depends.
Pronouns as Subjects
When pronouns act as subjects in the sentence, meaning they’re the ones doing something, the correct pronouns to use are: I, he, she, it, we, and they.
I went to the park.
He played basketball.
They are having pizza.
Pronouns as Objects
When the pronouns are objects, meaning something is happening to them, the correct ones to use are: me, him, her, it (that one is the same no matter what), us, and them.
Jacob invited me to the park.
Lisa played basketball with him.
Michael brought pizza home for them.
Where it becomes tricky (and where most people make mistakes) is when we have a compound subject or a compound object. That simply means we have two or people. The same rules apply, so you need to consider: Is it a subject or an object?
Jacob and I went to the park. (subject)
Jacob invited Tina and me to the park. (object)
He and Lisa played basketball. (subject)
Lisa played basketball with Tina and him. (object)
Michael and they are having pizza. (subject – sounds weird, but it’s right)
Michael brought home pizza for them and me. (object)
The easiest way to figure it out if you’re not sure is to remove the other person from the sentence. Usually, it will immediately sound correct one way or the other. For example, does it sound right to say: “My cousin invited I to the party.”? Of course not: My cousin invited Tanya and me to the party.