A high-quality estimate of the mean IQ of a country requires giving a well-validated test to a nationally representative sample, which usually is not feasible in developing countries. So, we used a convenience sample and four corrections based on theory and empirical findings to arrive at a good-quality estimate of the mean IQ in Bali. Our study used N = 50 Balinese (age between 7 and 46 years, M = 16.86) who took the Standard Progressive Matrices. Correcting for caste membership, school attendance, age distribution, and FLynn-effect gains resulted for the entire Balinese population in an IQ of 79, for adults of 75, and for children of 84. The validity of results is discussed. (Contains 1 table.)