Assumption 1: Network research focusses on the relationship and not the individual.- Assumption 2: Identities - what we are, we become through relationships.- Assumption 3: Two, three, under 10, many: Basic rules of structure formation.- Assumption 4: Strength of relationships and what that means for us.- Assumption 5: Behind our backs: Relationship structures work even when we are not aware of them.- Assumption 6: The structure of relationships limits us.- Assumption 7: Our own relationship arrangement is determined by others.- Assumption 8: What you know about the network is decisive for your behaviour: Cognitive social structure.- Assumption 9: The structure of relationships explains people's behaviour and attitudes.- Assumption 10: Our culture emerges in networks.- Assumption 11: Bimodal networks: what you can know about relationships without asking those involved.- Assumption 12: Organisations relate to each other through shared memberships.- Conclusion.- What you got out of the book.