In the beginning or at the beginning?
Although in the beginning and at the beginning can be used interchangeably when we don’t need to be very exact, there is a difference that is worth noting. The preposition we use changes the meaning of the expression, so read on to discover the difference.

Prepositions in English
Prepositions can be used to indicate, among other things, time, location and direction. The preposition “in” means “inside”, while “at” points to a particular location or position. Both words can be used to express relationships in space and time.
In the beginning vs. at the beginning
At the beginning refers to the moment when something began – the other phrase can also be used in this sense. For example, we could say “She fell asleep at the beginning of the movie”, meaning that she was dozing off soon after the movie started.
However, when you use in the beginning, the sense can change slightly. If we consider the same example, “She fell asleep in the beginning of the movie”, it could logically be followed by “…but she woke up later”. That’s because this expression can also mean “at first” or “initially” and is often contrasted with what happened later.
The difference is even more pronounced when we look at the phrases at the end (“at the point when something came to a close”) and in the end (“finally”, “eventually”, “at last”).
Now that the difference is clear, take a look at a few more examples to help you remember.
She’d tried standing her ground in the beginning, but three against one was never a fair fight, and she’d quickly learned her lesson.
One Hundred Years of Solitude (1967) by Gabriel Garcia Marquez
Finally, in the beginning of December, Úrsula burst into the workshop all upset.
Ophie’s Ghosts (2021) by Justina Ireland
And then he remembered his own voice speaking words that at the time he did not understand himself, at the beginning of their journey: I have something to do before the end.
The Two Towers (1954) by J. R. R. Tolkien