I realize that this may be a simple task, however I've not worked with Access much and am having trouble using drop boxes from a form to Filter a Report. The code is

    DoCmd.OpenReport "State_Safety_Workplan_Report", acViewPreview
    With Report_State_Safety_Workplan_Report.Report
        .Filter = "[Cost]=" & idCost
        .FilterOn = True
    End With

where idCost is just a variable with either L,M,or H in it. When I press the command button that this is tied to it opens the report and then prompts me with a dialog box and the text in the dialog box is whatever idCost is. I'm not sure what the correct code is but any help with what the correct code is would be very much appreciated.

Try something like this:
Note the two commas in a row before the WHERE condition.

Greg Serrano
Michigan Dept. of Environmental Quality, Air Quality Division