There is a one-time $5 membership fee when you open your account.
You can open an account online or at any local branch. Arrowhead membership is open to any person who lives, works, or worships in San Bernardino or Riverside Counties or select cities in southern Los Angeles County, Arizona, and Nevada; anyone employed by the State of California or is an immediate family member of a current member.3
You'll need the same information that's required when opening an individual account-- but you'll need it for both applicants.
Accounts for minors may be established at any branch location.