Hi Darren,  Thanks for your valuable response.I followed your instruction and added the "zc" to the last place of arcpy.MakeXYEventLayer_management(....., zc). I also checked my .xls file for the "zc" data, etc. - see the attched .xls file.I executed my revised Python script in the Python Window of my ArcGIS 10.0:>>> # scMakeXYlayerZ.py   for 10 points of ApgRImmrp:   X-, Y-, and Z-coord in the xls & the .py file
... # Description: Creates an XY layer and uses CopyFeatures to save it to a layer file
... # Author: ESRI - modified by Scott Chang per Arkadiusz Matoszka, Wayne Whitley and Darren Wiens 
... # (Date:  1 Nov 2012)
... # import system modules 
... import arcpy
... from arcpy import env
... # Set environment settings
... # env.workspace = r"C:\TEMP\BS_Test.gdb"         # New!!!  (per Arek)
...  
... try:
...     # Set the local variables
...     # in_Table = "firestations.csv"
...     tb = r"C:\TEMP\WritingGeometries\ApgRImmrpWGSxyz.xls\ApgRImmrpWGS$"
...     xc = "X"
...     yc = "Y"
...     zc = "Z"
...     out_Layer = "Pointlocations_layer"
...     saved_Layer = r"c:\TEMP\APGriMMRPBHsWellZ.shp"     # not .layer!!!
...  
...     # Set the spatial reference
...     # spRef = r"Coordinate Systems\Projected Coordinate Systems\Utm\Nad 1983\NAD 1983 UTM Zone 11N.prj"
...     spRef = r"Coordinate Systems\Geographic Coordinate System\World\WGS 1984" 
...  
...     # Make the XY event layer...
...     arcpy.MakeXYEventLayer_management(tb, xc, yc, out_Layer, spRef, zc)  # zc should be last (per Darren)
...  
...     # Print the total rows
...     print arcpy.GetCount_management(out_Layer)
...  
...     # Save to a layer file
...     # arcpy.SaveToLayerFile_management(out_Layer, saved_Layer)
...     arcpy.CopyFeatures_management(out_Layer, saved_Layer)      # New!!! (per Arek)
... except:
...     # If an error occurred print the message to the screen
...     print arcpy.GetMessages()
... 
ERROR 000622: Failed to execute (Make XY Event Layer). Parameters are not valid.
ERROR 000628: Cannot set input into parameter spatial_reference.
>>> 
It did not work at all-ERRORS 000622 and 000628 again.  Please kindly help and advise again.Thanks in advance,Scott Chang