L.A.
Hi K.. Hopefully some Santa Clara Mamasource readers will hook up with you. But you can also look for a local playgroup on a this webpage:
http://www.earthskids.com/playgroups.aspx
It lists playgroup info for the South Bay, including Santa Clara. You may especially want to check out the Las Madres group, as it is organzied by year of child, and this would be a great way to meet moms with babies in your area!
Besides organizing a playgroup, Las Madres offers some parent education plus the parents do babysitting exchange. Many of them will also have other (older) children as well, so you can make some great friends for yourself and the kids.
Also, you didn't mention if your 3 year old is in preschool...but since you are in Santa Clara you might want to check out the wonderful Santa Clara Parents Nursery School. Check them out on the web here:
http://scpns.ca.campusgrid.net/home
Your daughter would only go 3 mornings a week for about 2 1/2 hours, and you would stay and help out on one of those days each week. So not only would she meet kids and have a great time, but because you stay and work one day you would meet other parents.
Plus, because it's a co-op its the most inexpensive preschool option out there. And the teachers are wonderful! My youngest has gone all the way through SCPNS and he loved it.
The only hitch would be finding child care for 3 hours once a week for your baby. If a family member or neighbor can't help you out, the Las Madres group may be able to. Or ask at the school if other parents can refer you to a babysitter -- as many of the moms have babies and/or part time jobs.
Good Luck! Email me if you have any questions.