Among the issues that concern policy-makers is the question of the size and characteristics of the haredi population, given that this population group has the highest fertility rate (average number of children a woman is expected to bear during her lifetime) in Israel.In order to assess the characteristics of a population, however, it is necessary to define it. Given the lack of an official method for identifying the haredi population, a number of methods are used to estimate its size: 1. Identification based on statistics regarding education (last educational institution attended) and military service, using the data of the Central Bureau of Statistics or the National Insurance Institute; 2. Identification based on patterns of voting for haredi parties; 3. Direct identification based on subjective self-definition.According to the Central Bureau of Statistics’ 2015 Labor Force Survey, about 29% of Jewish households in Jerusalem are haredi.The survey also found that the average haredi household in Jerusalem has 5.0 persons, compared with 3.0 for religiously observant (non-haredi) households in the city. Because of the size of haredi households, the estimated number of haredi persons in the capital is significantly higher than the estimated number of households, and accounts for 39% of Jerusalem’s Jewish population (203,400 persons).It is also possible to identify the haredi population using election results. Voting districts that meet the following two criteria are considered haredi: those in which more than 50% of the population voted for United Torah Judaism or Shas, and those in which out of that 50%, at least 25% of all voters in the district voted for United Torah Judaism. Calculations of the population residing in these statistical districts relied on data from the Statistical Yearbook of Jerusalem, according to which 39% of Jerusalem’s Jewish population is haredi (203,830 persons).Finally, there is the direct identification estimation. According to the Annual Social Survey of the Central Bureau of Statistics, during 2013-2015, on average, 34% of Jerusalem’s Jewish population defined itself as haredi. But because the annual social survey is conducted among persons aged 20 and above, this figure can be sharpened by supplementing it with a numerical estimate of the haredi population that accounts for the city’s children. Using educational data from the Statistical Yearbook of Jerusalem and approximating the number of infants and nursery-aged children (who are not counted in education data) on the basis of Yearbook figures for school-aged children, we estimate Jerusalem’s haredi population at 216,500 persons, constituting 43% of the Jewish population.In short, we remain confused, though with a better understanding of the large proportion of the population represented by the haredim. It is important to bear in mind that this population group also has diverse characteristics within itself and is constantly changing, so perhaps in a few years the ways we estimate the size of this population will change. Translated by Merav Datan.