Just for anyone wondering, as per joshpadnick's great suggestions, you can specify other AWS account's users/roles via Principal in a policy as well. Just use

Just for anyone wondering, as per joshpadnick's great suggestions, you can specify other AWS account's users/roles via Principal in a policy as well. Just use the other AWS account in the ARN. edit: if you want to do so via policies that is I'd be interested to see your team's workflow for multiple accounts @joshpadnick.