How to attract vault members?

There are multiple ways to get more Shelter Dwellers:

- Lunchboxes

There is a chance to get a new dweller every time you open one of those boxes

- Make Babies

You can assign a male and a female dweller to the Living Quarters, now it's all about the honey and the bees, after a short while your Female dweller will be pregnant. note Pregnant dwellers are less efficient and therefore produce fewer resources.

- Radio Station

As soon as you hit a population of 20, you can build a Radio Station; this will attract more dwellers to the vault. You need to assign high charisma dwellers to the radio station to improve the success rate.

- Explore the Wasteland

Many guides point out that exploring the wasteland has an effect in attracting more dwellers to the vault (I'm just mentioning this for a complete list, as I can't confirm this works.)