Some embodiments include an integrated assembly having a channel-material-pillar extending vertically through a stack of alternating conductive levels and insulative levels. The channel-material-pillar includes a first semiconductor material. A second semiconductor material is directly against an upper region of the channel-material-pillar. The second semiconductor material has a higher dopant concentration than the first semiconductor material and joins to the first semiconductor along an abrupt interfacial region such that there is little to no mixing of dopant from the second semiconductor material into the first semiconductor material. Some embodiments include methods of forming integrated assemblies.