Take a look here: http://dre.ca.gov/pdf_docs/relaw.pdf
read section 10131 but pay particular interest to section 10131.01
Here are a few excerpts:
"10131. A real estate broker within the meaning of this part is a person who, for a compensation or in expectation of a compensation, regardless of the form or time of payment, does or negotiates to do one or more of the following acts for another or others:
(b) Leases or rents or offers to lease or rent, or places for rent, or solicits listings of places for rent, or solicits for prospective tenants, or negotiates the sale, purchase or exchanges of leases on real property, or on a business opportunity, or collects rents from real property, or improvements thereon, or from business opportunities.
However, subsection 10131.01 states:
"10131.01. (a) Subdivision (b) of Section 10131 does not apply to:
(2) any person or entity, including a person employed by a real estate broker, who, on behalf of another or others, solicits or arranges, or accepts reservations or money, or both, for transient occupancies described in paragraphs (1) and (2) of subdivision (b) of Section 1940 of the Civil Code, in a dwelling unit in a common interest development, as defined in Section 1351 of the Civil Code, in a dwelling unit in an apartment building or complex, or in a single-family home"
What this subsection means is that if you are an individual, you don't need a broker's license. However, if you read on you will see that is also says that if you are employed by a PM firm, there has to be a broker of record, the following sections explain the broker's responsibilities. It follows then that if it's your firm, you need a broker's license.
As Larry S wrote, you can only manage residential property and there has to be an on site manager if it's 16+ units