diff --git a/laboratory/api-src/org/labkey/api/laboratory/assay/DefaultAssayParser.java b/laboratory/api-src/org/labkey/api/laboratory/assay/DefaultAssayParser.java
index bbcd2ac4..a1a33f32 100644
--- a/laboratory/api-src/org/labkey/api/laboratory/assay/DefaultAssayParser.java
+++ b/laboratory/api-src/org/labkey/api/laboratory/assay/DefaultAssayParser.java
@@ -26,6 +26,7 @@
 import org.json.JSONArray;
 import org.json.JSONObject;
 import org.labkey.api.collections.CaseInsensitiveHashMap;
+import org.labkey.api.data.CompareType;
 import org.labkey.api.data.Container;
 import org.labkey.api.data.ConvertHelper;
 import org.labkey.api.data.DbSchema;
@@ -462,13 +463,30 @@ protected void validateRows(List<Map<String, Object>> rows, ImportContext contex
         errors.confirmNoErrors();
     }
 
+    /**
+     * Returns the set of container ids in which an assay run template for a request in the given container may
+     * legitimately live: the container itself, plus its parent when the request runs in a workbook (mirroring the
+     * run-template picker, which sources templates from Laboratory.Utils.getQueryContainerPath). Used to scope
+     * assay_run_templates lookups to the request's folder tree without reaching an unrelated container.
+     */
+    public static List<String> getTemplateContainerIds(Container c)
+    {
+        List<String> ids = new ArrayList<>();
+        ids.add(c.getId());
+        if (c.isWorkbook())
+            ids.add(c.getParent().getId());
+        return ids;
+    }
+
     protected void saveTemplate(ViewContext ctx, int templateId, int runId) throws BatchValidationException
     {
         try
         {
-            //validate the template exists
+            //validate the template exists in (or above) this container
             TableInfo ti = DbSchema.get("laboratory").getTable("assay_run_templates");
-            TableSelector ts = new TableSelector(ti, new SimpleFilter(FieldKey.fromString("rowid"), templateId), null);
+            SimpleFilter filter = new SimpleFilter(FieldKey.fromString("rowid"), templateId);
+            filter.addCondition(FieldKey.fromString("container"), getTemplateContainerIds(_container), CompareType.IN);
+            TableSelector ts = new TableSelector(ti, filter, null);
             if (ts.getRowCount() == 0)
             {
                 throw new BatchValidationException(Collections.singletonList(new ValidationException("Unknown template: " + templateId)), null);
@@ -586,7 +604,9 @@ protected Map<String, Map<String, Object>> getTemplateRowMap(ImportContext conte
 
         TableInfo ti = DbSchema.get("laboratory").getTable("assay_run_templates");
 
-        TableSelector ts = new TableSelector(ti, new SimpleFilter(FieldKey.fromString("rowid"), templateId), null);
+        SimpleFilter filter = new SimpleFilter(FieldKey.fromString("rowid"), templateId);
+        filter.addCondition(FieldKey.fromString("container"), getTemplateContainerIds(_container), CompareType.IN);
+        TableSelector ts = new TableSelector(ti, filter, null);
         Map<String, Object>[] maps = ts.getMapArray();
         if (maps.length == 0)
         {
diff --git a/laboratory/src/org/labkey/laboratory/assay/AssayHelper.java b/laboratory/src/org/labkey/laboratory/assay/AssayHelper.java
index ee4a9816..71086ff1 100644
--- a/laboratory/src/org/labkey/laboratory/assay/AssayHelper.java
+++ b/laboratory/src/org/labkey/laboratory/assay/AssayHelper.java
@@ -30,9 +30,11 @@
 import org.labkey.api.cache.CacheManager;
 import org.labkey.api.collections.CaseInsensitiveHashMap;
 import org.labkey.api.collections.CollectionUtils;
+import org.labkey.api.data.CompareType;
 import org.labkey.api.data.Container;
 import org.labkey.api.data.ContainerManager;
 import org.labkey.api.data.RuntimeSQLException;
+import org.labkey.api.data.SimpleFilter;
 import org.labkey.api.data.TSVMapWriter;
 import org.labkey.api.data.Table;
 import org.labkey.api.data.TableInfo;
@@ -50,7 +52,9 @@
 import org.labkey.api.laboratory.LaboratoryService;
 import org.labkey.api.laboratory.assay.AssayDataProvider;
 import org.labkey.api.laboratory.assay.AssayImportMethod;
+import org.labkey.api.laboratory.assay.DefaultAssayParser;
 import org.labkey.api.query.BatchValidationException;
+import org.labkey.api.query.FieldKey;
 import org.labkey.api.query.ValidationException;
 import org.labkey.api.security.User;
 import org.labkey.api.util.FileUtil;
@@ -131,16 +135,26 @@ public Map<String, Object> saveTemplate(User u, Container c, ExpProtocol protoco
             row.put("title", title);
             row.put("importMethod", importMethod);
             row.put("json", json.toString());
-            row.put("container", c.getId());
 
             if (templateId == null)
             {
+                row.put("container", c.getId());
                 row = Table.insert(u, ti, row);
             }
             else
             {
+                // Table.update operates by global PK; verify the template is reachable from this container
+                // (here, or the parent when in a workbook) before updating, and leave its container unchanged.
+                SimpleFilter filter = new SimpleFilter(FieldKey.fromString("rowid"), templateId);
+                filter.addCondition(FieldKey.fromString("container"), DefaultAssayParser.getTemplateContainerIds(c), CompareType.IN);
+                if (!new TableSelector(ti, filter, null).exists())
+                {
+                    errors.addRowError(new ValidationException("Unknown template: " + templateId));
+                    throw errors;
+                }
+
                 row.put("rowid", templateId);
-                row = Table.update(u, ti, row, templateId);
+                row = Table.update(u, ti, row, templateId);  // "container" intentionally absent -> not moved
             }
 
             return row;