You cannot adopt a child if the Social Worker has previously removed someone from the household, or if you've reached the max household size of 8 Sims.Assuming neither of those has happened, any Sim at the young adult stage or older can adopt.
 Interact with any phone and select the "Call Services" option, then select "Adoption Services."


The Sim must be on his or her home lot to adopt.
 When adopting, you get to choose between a girl and a boy, and between a baby, toddler, or child. You also get to name the kid, although the last name will always be the same as the Sim who made the phone call.The traits and appearance are always random, but you can improve future traits with a good upbringing.
 Within a game hour the kid should arrive at your house. Babies and toddlers are dropped off by a social worker, while children will ride a bike to your house.
Start with a stable household.
Phone the adoption services.
Choose a child.
Wait for the kid.
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