During this past year I have been on sabbatical in Israel conducting research and teaching at The Hebrew University in Jerusalem. In addition to my university responsibilities I have enjoyed traveling this beautiful country and learning about its rich history, culture, and people. Last week my family and I spent the weekend in an old Jewish Ultra-Orthodox neighborhood in an apartment of a distant relative.I knew that he had a large family but once we settled into our modest room I had a chance to meet his entire family: his wife and 9 children – ages 15 to 3 months. Large families are typical of the Ultra-Orthodox in Israel and, in fact, the family we spent the weekend with was considered to be a bit more “modern” considering that they had “only” 9 children.There were many cultural, social, and family dynamics that fascinated me during the weekend the least of which was the question of how does a family of 11 live with just one bathroom??? However, as someone with an interest in sibling relationships, I was particularly attentive to the sibling interactions in this family. I was amazed by the apparent cohesion that existed among the children of this family. Each child seemed to feel they had a unique role in the family which the other siblings respected.Similar to my observations, several studies suggest that in larger families power is diversified more evenly among siblings. With each sibling feeling that they contribute to the family functioning there is less of an imbalance among siblings minimizing sibling conflict. In small families an older sibling may have more control producing a power inequality. Additionally, large families are more likely to have a group feeling compared to smaller families contributing to cohesion between family members. With a bunch of children, siblings in a large family may see themselves as a team helping to create closeness.Studies actually do show that children from larger families are more likely to be altruistic, cooperative, and interdependent than children from smaller families. One final advantage of having many children is that siblings in larger families have more options of siblings to interact with, creating sibling subgroups, which may contribute to closer sibling relationships.On the other hand, studies also point to several advantages of having smaller families. Most significantly, in larger families, where resources may be scarce, siblings may be more likely to experience conflict in competition for the limited resources in comparison to siblings from smaller families in which resources are adequate. Mom only has a limited amount of time to read books during bedtime. With 4 or 5 children wanting some quality time with Mom some competition among siblings is only natural.To try and make sense of these inconsistent findings the following may be concluded. The advantages of larger families are the more diversified power structure among siblings which reduces sibling imbalance, the creation of a group orientation, and the potential for the formation of sibling subgroups. In contrast, the disadvantage for larger families is the potential for conflict in competition for limited resources.Bottom line: In both large and small families problems may surface. Awareness of the issues we just reviewed can help direct parents in monitoring these problems and intervening when problems arise. For example, in larger families parents can make sure that children do not perceive limited parental resources by scheduling individual time with each child. In smaller families parents can diversify family responsibilities and not simply rely on the oldest child for help. In order to create a group orientation parents may want to foster relationships between their children and extended family members to help develop a sense of group cohesion.There are ways of creating a beautiful sense of cohesion between children in a family without having to live with just one bathroom.