Someone on Apple’s support discussion group claimed “this can’t be done.” Apple explicitly supports shared calendars, but not shared contacts. They probably haven’t figured out how to deal with two people updating things at the same time.
Then I found this terrific article by Lena Shore. Most of us have our contacts saved in a “personal” iCloud account. Shore’s approach is to set up a “household” iCloud account. You save the shared contact list to the household account. Then you enable Contacts under both accounts. Everyone who does this will see both their personal list and the household list.
Shore’s article is very specific about how to do this. It’s worth following the instructions step by step.
However, there is one little wrinkle when it comes to iOS devices: the latest versions of the Settings app is a bit different from the one Shore describes. In Step 9, the “Add Account” function now appears under “Passwords&Accounts.” Be sure to add the household account as an iCloud account. There will be a series of switches for activating different services on the account: be sure to enable Contacts.
Another wrinkle for longer-term Apple users: you may already have a household Apple account of some sort. Our household has had a single iTunes account ever since we started using iPods in the previous decade. When iCloud arrived we created individual accounts for that. Go ahead and use your household iTunes account for shared contacts.
Apple doesn’t seem to put its official seal of approval on this procedure. This probably works fine if you make occasional changes to your shared contact list. If members of your household update the contact list every time they read email, this technique might fail. You don’t want two different people (devices) to try to make changes at the same time. That’s just a guess on my part.
I’m trying this this because my wife’s copy of our contact list disappeared from her phone and iCloud account. I can’t figure out what caused it to happen, though it probably coincided with changing iPhones and changing rules for connecting to Outlook at work.
If you’re doing this, you really need a Mac desktop, and you should make regular backups of your contact list.