Epithelial cells prefer to pack in a two-dimensional polygonal array that minimizes energy expenditure. However, because the arrangements of cells within tissues are intimately tied to tissue function, epithelial cell rearrangements occur frequently during development. Now, on p. 1385, Robert Simone and Stephen DiNardo begin to unravel how subsets of cells in the ventral epidermis of the Drosophila embryo realign into parallel columns that produce denticles, ridge-like projections in the cuticle. Using live imaging, the researchers show that column formation by these subsets of cells involves the alignment of their anteroposterior boundaries, shrinkage of certain cell interfaces, and the conversion of three-cell to four-cell junctions. In addition, they report that non-muscle Myosin II and the polarity proteins Discs large and Bazooka (Par3) exhibit a complex localisation pattern along the cell interfaces and that Myosin II or Discs large depletion disrupts junctional conversion and cell alignment. Together, these results suggest that actomyosin contractility and polarity protein function help to drive fine-scale epithelial cell rearrangements.