The present disclosure includes apparatuses and methods related to determining population count. An example apparatus comprises an array of memory cells coupled to sensing circuitry. The apparatus can include a controller configured to cause: summing, in parallel, of data values corresponding to respective ones of a plurality of first vectors stored in memory cells of the array as a data value sum representing a population count thereof, wherein a second vector is stored as the plurality of first vectors, and wherein each first vector of the plurality of first vectors is stored in respective memory cells of the array that are coupled to a respective sense line of a plurality of sense lines; and iteratively summing, in parallel, of data value sums corresponding to the plurality of first vectors to provide a single data value sum corresponding to the second vector.