If you are an ASA Member:
Since you are already a national member of the American Statistical Association (ASA) you can join the San Diego Chapter (SDASA) online via the ASA website: ASA Member Login, select Manage My Account-> Membership->Add a Chapter or Section.
If you only want to become a local SDASA member:
Please fill out the google form: San Diego Local Chapter Member Sign-up Form
and pay the membership dues using the PayPal link below: