Is there a recommended way to dynamically remove specific Steppable objects from the schedule? I don't remember seeing any discussion of this in the tutorials and none of the schedule methods seem to enable single object removal. I want to be able to treat 'dead agents' as such. Right now, I simply check a boolean to see whether a steppable instance is alive or not at the beginning of the step(). For low numbers of steppables and time steps, this is reasonable solution, but for long runs and large numbers of steppables it may add undesirable overhead via the main model, graphs/charts, etc. I am dynamically removing Steppables from a SparseGrid2D. Web tutorial 1 (how to use JFree) is excellent and got me off the ground quickly. Perhaps you could update the tutorial to reflect a newer release and the fact that the class hierarchy has changed a little. For example, the import statement in the section "Adding a line chart to the model" should now read: import org.jfree.data.xy.XYSeries; ^^ new Thanks, Tony Bigbee