To facilitate the exploitation of embryonic stem cells (ESCs) and ESC‐derived cells, scale‐up of cell production and optimization of culture conditions are necessary. Conventional ESC culture methods are impractical for large‐scale cell production and lack robust microenvironmental control. We developed two stirred‐suspension culture systems for the propagation of undifferentiated ESCs—microcarrier and aggregate cultures—and compared them with tissue‐culture flask and Petri dish controls. ESCs cultured on glass microcarriers had population doubling times (∼14–17 hours) comparable to tissue‐culture flask controls. ESC growth could be elicited in shear‐controlled stirred‐suspension culture, with population doubling times ranging between 24 and 39 hours at 100 rpm impeller speed. Upon removal of leukemia inhibitory factor, the size‐controlled ESC aggregates developed into embryoid bodies (EBs) capable of multilineage differentiation. A comprehensive analysis of ESC developmental potential, including flow cytometry for Oct‐4, SSEA‐1, and E‐cadherinprotein expression, reverse transcription–polymerase chain reaction for Flk‐1, HNF3‐β, MHC, and Sox‐1 gene expression, and EB differentiation analysis, demonstrated that the suspension‐cultured ESCs retained the developmental potential of the starting cell population. Analysis of E‐cadherin^−/− and E‐cadherin^+/− cells using both systems provided insight into the mechanisms behind the role of cell aggregation control, which is fundamental to these observations. These cell‐culture tools should prove useful for both the production of ESCs and ESC‐derived cells and for investigations into adhesion, survival, and differentiation phenomena during ESC propagation and differentiation.