It is a widely held view that “nobody knows you better than yourself.” However, the low validity of self-estimates of intelligence and other abilities indicated by a considerable body of research does not support this notion. Individuals overestimate themselves and do so particularly for domains in which they perform poorly (the so-called Dunning-Kruger effect). Interestingly, intelligence estimates given by others are equally accurate or sometimes even more accurate than self-estimates. This chapter provides an overview of research on self- and other-estimates of intelligence and potential moderators of their accuracy. It also aims to bring the research lines on self- and other-estimates of intelligence together within the framework of the self-other knowledge asymmetry (SOKA) model proposed by Simine Vazire. The ability to predict for which intelligence subfactors one of the two perspectives might provide more accurate estimates has implications for both research and practical fields like vocational counseling.