diff --git a/makefile-templates/Makefile.content b/makefile-templates/Makefile.content
index 5a0678c..a478914 100755
--- a/makefile-templates/Makefile.content
+++ b/makefile-templates/Makefile.content
@@ -31,11 +31,21 @@
 
 ################################################################################
 #
+# Required Environment Variables
+#
+# TEACHING_SHARED
+#	This variable specifies the path to the top level of the teaching
+#	shared directory hierarchy (e.g., /path/to/Teaching/Shared).
+#
+TEACHING_SHARED?=$(error The required environment variable TEACHING_SHARED has not been defined. It should point to the root level of the shared teaching directory (e.g., /path/to/Teaching/Shared))
+
+
+################################################################################
+#
 # Set up paths to makefile include directories.
 #
 # GLOBAL_HANDBOOK_INCLUDE is the global include directory in the "Shared"
-# hierarchy, and should ideally be defined as an environment variable.
-# It's an error not to define this variable.
+# hierarchy, and is defined relative to the root of that hierarchy.
 #
 # LOCAL_HANDBOOK_INCLUDE is the local include directory for this
 # particular paper, and is defined relative to the current execution
@@ -43,7 +53,7 @@
 # directory hierarchy, this has to be defined by the makefile's calling
 # environment. It's an error not to define this variable.
 #
-GLOBAL_HANDBOOK_INCLUDE?=$(error The environment variable GLOBAL_HANDBOOK_INCLUDE has not been defined)
+GLOBAL_HANDBOOK_INCLUDE?=$(TEACHING_SHARED)/Authoring/Handbook/make-includes
 
 LOCAL_HANDBOOK_INCLUDE?=$(error The environment variable LOCAL_HANDBOOK_INCLUDE has not been defined)