The difference between meaningfulness and happiness was the focus of an investigation I worked on with my fellow social psychologists Kathleen Vohs, Jennifer Aaker and Emily Garbinsky, published in the Journal of Positive Psychology this August. We carried out a survey of nearly 400 US citizens, ranging in age from 18 to 78. The survey posed questions about the extent to which people thought their lives were happy and the extent to which they thought they were meaningful. We did not supply a definition of happiness or meaning, so our subjects responded using their own understanding of those words. By asking a large number of other questions, we were able to see which factors went with happiness and which went with meaningfulness.