diff --git a/lib/index.js b/lib/index.js
index 121cea4..9230bc0 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -122,9 +122,11 @@ module.exports = (function() {
 
         var sheet = self.loadSheet(sheetName);
 
-        var sheetData = sheet.root.find("sheetData"),
+        var dimension = sheet.root.find("dimension"),
+            sheetData = sheet.root.find("sheetData"),
             currentRow = null,
             totalRowsInserted = 0,
+            totalColumnsInserted = 0,
             namedTables = self.loadTables(sheet.root, sheet.filename),
             rows = [];
 
@@ -213,6 +215,11 @@ module.exports = (function() {
             // Update row spans attribute
             if(cellsInserted !== 0) {
                 self.updateRowSpan(row, cellsInserted);
+
+                if(cellsInserted > totalColumnsInserted) {
+                    totalColumnsInserted = cellsInserted;
+                }
+
             }
 
             // Add newly inserted rows
@@ -232,7 +239,17 @@ module.exports = (function() {
         // Update placeholders in table column headers
         self.substituteTableColumnHeaders(namedTables, substitutions);
 
-        // TODO: Set <dimension />
+        // Update <dimension /> if we added rows or columns
+        if(totalRowsInserted > 0 || totalColumnsInserted > 0) {
+            var dimensionRange = self.splitRange(dimension.attrib.ref),
+                dimensionEndRef = self.splitRef(dimensionRange.end);
+
+            dimensionEndRef.row += totalRowsInserted;
+            dimensionEndRef.col = self.numToChar(self.charToNum(dimensionEndRef.col) + totalRowsInserted);
+            dimensionRange.end = self.joinRef(dimensionEndRef);
+
+            dimension.attrib.ref = self.joinRange(dimensionRange);
+        }
 
         // Write back the modified XML trees
         self.archive.file(sheet.filename, etree.tostring(sheet.root));
diff --git a/test/crud-test.js b/test/crud-test.js
index fc847fb..dcb7953 100644
--- a/test/crud-test.js
+++ b/test/crud-test.js
@@ -91,6 +91,9 @@ describe("CRUD operations", function() {
                 var sharedStrings = etree.parse(t.archive.file("xl/sharedStrings.xml").asText()).getroot(),
                     sheet1        = etree.parse(t.archive.file("xl/worksheets/sheet1.xml").asText()).getroot();
 
+                // Dimensions should be updated
+                buster.expect(sheet1.find("./dimension").attrib.ref).toEqual("B2:F9");
+
                 // extract date placeholder - interpolated into string referenced at B4
                 buster.expect(sheet1.find("./sheetData/row/c[@r='B4']").attrib.t).toEqual("s");
                 buster.expect(
@@ -199,6 +202,9 @@ describe("CRUD operations", function() {
                 var sharedStrings = etree.parse(t.archive.file("xl/sharedStrings.xml").asText()).getroot(),
                     sheet1        = etree.parse(t.archive.file("xl/worksheets/sheet1.xml").asText()).getroot();
 
+                // Dimensions should be updated
+                buster.expect(sheet1.find("./dimension").attrib.ref).toEqual("B2:F9");
+
                 // extract date placeholder - interpolated into string referenced at B4
                 buster.expect(sheet1.find("./sheetData/row/c[@r='B4']").attrib.t).toEqual("s");
                 buster.expect(
@@ -292,6 +298,9 @@ describe("CRUD operations", function() {
                 var sharedStrings = etree.parse(t.archive.file("xl/sharedStrings.xml").asText()).getroot(),
                     sheet1        = etree.parse(t.archive.file("xl/worksheets/sheet1.xml").asText()).getroot();
 
+                // Dimensions should be set
+                buster.expect(sheet1.find("./dimension").attrib.ref).toEqual("B2:D6");
+
                 // C4 should have moved left, and the old B4 should now be deleted
                 buster.expect(sheet1.find("./sheetData/row/c[@r='B4']/v").text).toEqual("101");
                 buster.expect(sheet1.find("./sheetData/row/c[@r='C4']")).toBeNull();
@@ -344,6 +353,9 @@ describe("CRUD operations", function() {
                 var sharedStrings = etree.parse(t.archive.file("xl/sharedStrings.xml").asText()).getroot(),
                     sheet1        = etree.parse(t.archive.file("xl/worksheets/sheet1.xml").asText()).getroot();
 
+                // Dimensions should be updated
+                buster.expect(sheet1.find("./dimension").attrib.ref).toEqual("B2:K17");
+
                 // Marker above table hasn't moved
                 buster.expect(sheet1.find("./sheetData/row/c[@r='B4']/v").text).toEqual("101");
 
@@ -485,6 +497,9 @@ describe("CRUD operations", function() {
                     table2        = etree.parse(t.archive.file("xl/tables/table2.xml").asText()).getroot(),
                     table3        = etree.parse(t.archive.file("xl/tables/table3.xml").asText()).getroot();
 
+                // Dimensions should be updated
+                buster.expect(sheet1.find("./dimension").attrib.ref).toEqual("B2:L29");
+
                 // Named ranges have moved
                 buster.expect(workbook.find("./definedNames/definedName[@name='BelowTable']").text).toEqual("Tables!$B$18");
                 buster.expect(workbook.find("./definedNames/definedName[@name='Moving']").text).toEqual("Tables!$G$8");