This article investigates the use of visual artifacts to represent time. Timelines, or “Gantt charts,” are widely used for scheduling, budgeting, and project management, and they are woven into the fabric of organizational life. Timelines embody objectivist, monotemporal assumptions about time yet allow organizational and occupational subgroups with different assumptions to negotiate and manage time prospectively and retrospectively. Timelines thus function as temporal boundary objects, visual representations of time that are both interpretively flexible and robust.