Hybrid tree/mesh overlays for data delivery involve using a tree overlay network and a mesh overlay network to delivery a data stream via a push mechanism and a pull mechanism, respectively. In an example embodiment, a network node enters a mesh overlay network and attaches to a tree overlay network. In operation, the network node receives data blocks of a data stream over the tree overlay network via a push mechanism. The network node ascertains if a data block is not received over the tree overlay network. If a data block is missing, the network node retrieves the missing data block over the mesh overlay network via a pull mechanism. In another example embodiment, the tree overlay network includes a subset of nodes forming a tree-based backbone. Network nodes that are identified as being stable may join the backbone and provide the data stream to other nodes.