In this chapter, the authors examine the social mood context of the time periods they studied, and explain the tool they used to assess the mood of Finland’s popular music, and describe the two phases of testing they conducted. Robert Prechter’s socionomic theory proposed that social mood—the unconscious, aggregate levels of optimism and pessimism in a society—influences the tenor and character of social actions. The authors aim to compare the levels of optimism and pessimism in a random sample of songs from the pop chart in Finland in 2006 to a comparable sample from 2009. They show that the 2009 sample is significantly more pessimistic than the 2006 sample. The Eurobarometer Life Satisfaction Survey reveals that slightly more people in Finland were satisfied with their lives in the spring of 2009 than in the spring of 2006. The concept was originally developed in the USA, yet the scale has been adapted for clinical use in Finland.