Can I legally change my last name to my boyfriends last name without being married.?

You file an petition to change your name in the Superior Court. The process is a bit longer than can be described here, but the California Superior Court's website has a good "how to"guide for an adult changing their name. Check out the page at http://www.courts.ca.gov/1051.htm. It shouldn't be too difficult as these are not adversarial matters where you are fighting someone else to get what you want. If you follow the procedure, generally you'll get the legal name change from the Court. Be sure, however, to follow-up on the post-order requirements such as changing your name with Social Security, etc... David L. Gibbs, Esq.The Gibbs Law Firm, APCSan Clemente, Californiagibbslaw.com *Due to the limitations of the Lawyers.com Forums, The Gibbs Law Firm, APC's (the "Firm") participation in responding to questions posted herein does not constitute legal advice, nor legal representation of the person or entity posting a question. No Attorney/Client relationship is or shall be construed to be created hereby. Further, information you provide to the Firm through this website is not confidential - it is available publicly to anyone visiting this website. The Firm shall have no obligation to keep the information you provide herein confidential in any context. The information provided herein by the Firm is general, and requires that the poster obtain specific legal advice from an attorney. The poster shall not rely upon the information provided herein as legal advice nor as the basis for making any decisions of legal consequence. As required by 11 U.S.C. §528, we must now disclose that, "We are a debt relief agency. We help people file for bankruptcy relief under the Bankruptcy Code. Assistance we provide with respect to Debt Relief may involve bankruptcy relief under the Bankruptcy Code."