Nobody hands you a memo the day your title changes. One day you're managing a calendar, the next you're supposedly managing a business, and the actual difference between those two things is rarely explained to you. It's just expected.
Here's the honest version. An EA's job is built around a person. You protect their time, manage their inbox, and make sure the right people get in the room. It's built around service to one person's day, and it's genuinely skilled work.
A Chief of Staff's job is built around a business. You stop protecting time and start protecting outcomes. The question changes from “is this on the calendar” to “is this going to move the number we care about.” You stop being the person who executes what's been decided and start being one of the people deciding what needs to happen.
That's the entire shift in one sentence: you move from owning tasks to owning outcomes. Everything else in this workbook sits on top of that one idea.
The tricky part is that most people get the title before they've made the shift. You get called Chief of Staff, but you're still operating like an EA with a bigger inbox. The title doesn't do the work for you. If you don't consciously reset how you show up, you'll keep doing the same job under a new name for a lot longer than you should.
Here's the flip side of that, and it matters just as much. Access and trust are almost never handed over all at once with a title. They get extended progressively: a meeting you're now included in, a number you're now shown, a decision you're now trusted to make without checking first, each one earned before the next is offered. In practice, you can already be doing real Chief of Staff work long before anyone calls it that. I lived this myself. There was a long stretch where I was already running the operating rhythm, managing the sensitive relationships, and owning the priorities before Chief of Staff was the official word for it. The work moved first. The title moved after. If you're reading this and recognizing yourself, you don't need the title to change first. You need to be able to prove the scope already has.