Can I privately record a conversation with another employee (without her knowledge)?

The answer is definitely no. California is a “two party consent” state — in other words, it is a crime to record or eavesdrop on any confidential communication, including a private conversation or telephone call, without the consent of all parties to the conversation. See California Penal Code, Section 632. It applies to telephone conversations, but to casual conversations in person as well.

The definition of “person” (recording the conversation) includes an individual, business association, partnership, corporation, limited liability company or other legal entity. Therefore, an employer can’t record conversations without permission either.