Use marijuana? Wish you used less? Thinking about quitting? An increasing number of people are using marijuana, and while many are able to do so without problems, some users suffer a number of ill effects. Those who do have ill effects often describe an inability to control their use, problems at home or work, or on their health (such as memory problems, low energy, low mood, or anxiety). If you are having problems related to your marijuana use and you are wanting to cut down or quit, participating in our clinical trial may help. Stanford University is currently conducting a confidential study to determine if a non-medication treatment, repetitive Transcranial Magnetic Stimulation (rTMS), can help frequent marijuana users reduce their use. All participants will receive counseling to assist them achieve their marijuana related goals at no charge. Compensation is available to participants to offset their time and travel. By participating in this trial you will be contributing to science and potentially the development of a new treatment to help others. To qualify for the study you must: -Be between the ages of 18 and 65 -Use marijuana regularly and have negative effects from your marijuana use -Want to quit or cut down on your marijuana use -Not have problematic use of other substances such as alcohol, opioids, or methamphetamine If you are interested in hearing more about this study please contact Brendan at (650) 490-8194, or by email at .