Obtaining a Master's degree is generally always worth the additional schooling - the more you know, the more exposure you get to different aspects of your field, the more you learn, the more marketable you become. A Master's degree will set you a part from other applicants in your field who may not have additional education or experience.
I agree with Kelly. A bachelors degree has become a lot more popular so in order to make more money and continue moving up it would be ideal to get a Masters degree. With a Bachelors in Social Work, you can apply for an advance standing 1 year Masters in Social Work program which will allow you to receive your Bachelors and Masters of Social Work within 5 years. I chose to graduate college in 3 years with my Bachelors in Sociology and go into a 2 year Masters in Social Work program. Just an additional year of college was worth it to me.