Mesenchymal condensation transduces minute mechanical forces to the cell nucleus, resulting in up or down-regulation of genes and, ultimately, the formation of the skeletal template. An understanding of the relationship between a cell’s mechanical environment and its shape and fate may open new possibilities to control cellular structure and function. Here we hypothesize that seeding density and protocol affect the fate and shape of live embryonic murine mesenchymal stem cells (MSCs) and their nuclei. We compared cellular and nuclear volume and shape between groups of a model MSC line (C3H10T1/2) seeded at, or proliferated from 5,000 cells/cm² to, one of three target densities to achieve targeted development contexts. Cell volume was shown to be dependent on initial seeding density whereas nucleus shape was shown to depend on developmental context but not seeding density. Both smaller cell volumes and flatter nuclei were found to correlate with increased expression of markers for mesenchymal condensation as well as chondrogenic and osteogenic differentiation but a decreased expression of pre-condensation and adipogenic markers. This study demonstrates that seeding density and protocol can be used to control stem cell shape and fate. These insights are expected to be scaleable to the three dimensional world of the cell during mesenchymal condensation, where prescribed boundary conditions are defined by proliferation of cells within an expanding albeit bounding envelope.