Some embodiments include an integrated assembly having a second deck over a first deck. The first deck has first memory cell levels, and the second deck has second memory cell levels. A pair of cell-material-pillars pass through the first and second decks. Memory cells are along the first and second memory cell levels. The cell-material-pillars are a first pillar and a second pillar. An intermediate level is between the first and second decks. The intermediate level includes a region between the first and second pillars. The region includes a first segment adjacent the first pillar, a second segment adjacent the second pillar, and a third segment between the first and second segments. The first and second segments include a first composition, and the third segment includes a second composition different from the first composition. Some embodiments include methods of forming integrated assemblies.