Social networking sites (SNSs) are immensely popular and allow for display of personal information, including references to depression. Evaluating displayed content on a SNS for research purposes requires a systematic approach and a precise data collection instrument. The purpose of this paper is to describe one approach to the development of a research codebook for depression so that others may develop and test their own codebooks for use in SNS research. The depression SNS research codebook was grounded in ethics, theory and clinical criteria.The key elements in the codebook developmental process included an iterative team approach to develop variables of interest and data collection sheet layout. Training protocols involve coding practice and reliability assessments. Interrater reliability remains a critical assessment tool. Codebook successes include consistently high interrater reliability. Challenges include time investment in coder training, SNS server changes, and social or cultural norms regarding public displays of mental health. We provide detailed information about a systematic approach to codebook development so that other researchers may use this structure to develop and test their own codebooks for use in SNS research. Future directions for the codebook include expanding areas of interest such as anxiety or other depression evaluation criteria, and expansion to other SNSs such as Twitter.