In every discussion about the demographic future of Jerusalem and its various neighborhoods, the residential patterns of 20-34-year-olds must be taken into consideration.A 2011-2015 analysis of the Jerusalem neighborhoods where people aged 20-34 constitute more than 40% of the adult (over 20-year-old) population teaches us about the preferred areas by both secular and observant young people on the one hand, and about the areas chosen by young haredi families on the other.The most prominent finding is that the haredi neighborhoods have the highest percentages of those 20-34, reaching as high as 60% of the adults in the Bayit Vegan neighborhood. In many Arab neighborhoods as well, young people comprise up to 51% of the adult population, one example being New Anata (Ras Shehada). Both these population groups are characterized by high fertility rates (3.23 among the Arabs, and 6.9 among the haredi population) and therefore their populations are younger relative to the general population of Israel.A deeper analysis teaches us about patterns of haredization in certain Jerusalem neighborhoods and about the neighborhoods preferred by secular and religious young people.In upper (western) Neveh Ya’acov, there has been a 15-percent continuous increase in the number of young people – from 3,840 in 2011 to 4,450 in 2015. This represents an increase from 45.5% in 2011 to 51% in 2015.In recent years haredization has been observed moving from the lower (eastern) part of the neighborhood (that has been haredi since its inception) to the upper part. When considering the young families (defined as having children up to age 9, and parents aged 25 to 39), the haredization in Neveh Ya’acov gives the area the highest percentage of young families among Jerusalem neighborhoods, where they comprise 62% of residents.When studying the concentrations of people aged 20 to 34, it emerges that the areas they prefer are the various parts of Nahlaot and the center of the city, in the triangle formed by the streets Jaffa, King George, and Agron, where they comprise between 41% and 53% of residents. These areas experienced an increase of 14% in the total number of young people between 2011 and 2015, when the numbers grew from 3,550 to 4,050. In the Rehavia neighborhood, young people constitute 43% of the adult population. The neighborhood is popular among students, and also among young haredi families from North America. The highest growth rate was recorded in the northern part of Rehavia adjacent to the Sha’arei Hesed neighborhood.For young families, Nahlaot leads among the non-haredi neighborhoods, where young families number about 51% of the adult residents. However, the percentage of children in the neighborhood is low relative to other neighborhoods such as Talpiot, Gilo, Pisgat Ze’ev, Ir Ganim and Nayot. The recorded high percentage is actually comprised of a very high concentration of 25-to-29-year-olds who don’t have children.Translated by Gilah Kahn.