It is safe to posit that human beings have been interested in their own inner mental experiences from the moment they became aware of them, arguably over 60,000 years ago (Leary, 2004). In sharp contrast, growth in the actual scientific examination of these inner experiences is remarkably recent (e.g., Csikszentmihalyi and Figurski, 1982; Klinger and Cox, 1987–1988; Goldstein and Kenen, 1988; Hurlburt, 1990). Inner speech, in particular, has been the focus of even more recent efforts (e.g., Morin et al., 2011; Brinthaupt and Dove, 2012; Hurlburt et al., 2013; Alderson-Day and Fernyhough, 2015; Alderson-Day et al., 2015). We present 14 articles that cover theoretical ideas as well as current research results pertaining to the measurement, frequency, content, and functions of inner experiences. In what follows we summarize some exciting key findings highlighted in this research topic.