diff --git a/Sources/VLModel.cpp b/Sources/VLModel.cpp
index d8755a5..3dc3fa6 100644
--- a/Sources/VLModel.cpp
+++ b/Sources/VLModel.cpp
@@ -541,3 +541,53 @@ void VLSong::DelNote(size_t measure, VLFraction at)
 	}
 }
 
+static void TransposePinned(int8_t & pitch, int semi)
+{
+	if (pitch == VLNote::kNoPitch)
+		return;
+
+	int pitchInOctave = pitch % 12;
+	int octave		  = pitch-pitchInOctave;
+	pitchInOctave	 += semi;
+	if (pitchInOctave < 0)
+		pitch		  = octave+pitchInOctave+12;
+	else if (pitchInOctave > 11)
+		pitch		  = octave+pitchInOctave-12;
+	else
+		pitch 		  = octave+pitchInOctave;
+}
+
+void VLSong::Transpose(int semi)
+{
+	for (int pass=0; pass<2 && semi;) {
+		int8_t low		= 127;
+		int8_t high	= 0;
+		for (int measure=0; measure<fMeasures.size(); ++measure) {
+			VLNoteList::iterator i = fMeasures[measure].fMelody.begin();
+			VLNoteList::iterator e = fMeasures[measure].fMelody.end();
+
+			for (; i!=e; ++i) {
+				if (i->fPitch == VLNote::kNoPitch)
+					continue;
+				i->fPitch	+= semi;
+				low			 = std::min(low, i->fPitch);
+				high		 = std::max(high, i->fPitch);
+			}
+		}
+		if (low < VLNote::kMiddleC-6 && high < VLNote::kMiddleC+7)
+			semi	+= 12;	// Transpose an Octave up
+		else if (low > VLNote::kMiddleC+7 && high > VLNote::kMiddleC+16)
+			semi 	-= 12;	// Transpose an Octave down
+		else
+			break;			// Looks like we're done
+	}
+	for (int measure=0; measure<fMeasures.size(); ++measure) {
+		VLChordList::iterator i = fMeasures[measure].fChords.begin();
+		VLChordList::iterator e = fMeasures[measure].fChords.end();
+
+		for (; i!=e; ++i) {
+			TransposePinned(i->fPitch, semi);
+			TransposePinned(i->fRootPitch, semi);
+		}
+	}
+}
diff --git a/Sources/VLModel.h b/Sources/VLModel.h
index 9b50e7f..efbe9c0 100644
--- a/Sources/VLModel.h
+++ b/Sources/VLModel.h
@@ -217,6 +217,7 @@ struct VLSong {
 	void AddNote(VLNote note, size_t measure, VLFraction at);
 	void DelChord(size_t measure, VLFraction at);
 	void DelNote(size_t measure, VLFraction at);
+	void Transpose(int semitones);
 
 	size_t	CountMeasures() const { return fMeasures.size(); }
 };
diff --git a/Sources/VLSheetView.mm b/Sources/VLSheetView.mm
index c6cf69e..73ed4d0 100644
--- a/Sources/VLSheetView.mm
+++ b/Sources/VLSheetView.mm
@@ -345,8 +345,24 @@ static float sFlatPos[] = {
 
 - (IBAction) setKey:(id)sender
 {
+	[[NSAlert alertWithMessageText:@"Transpose Song?"
+			 defaultButton:@"Transpose"
+			 alternateButton:@"Cancel"
+			 otherButton:@"Change Key"
+			 informativeTextWithFormat:
+				 @"Do you want to transpose the song into the new key?"]
+		beginSheetModalForWindow:[self window]
+		modalDelegate:self didEndSelector:@selector(setKey:returnCode:contextInfo:)
+		contextInfo:sender];
+}
+
+- (void)setKey:(NSAlert *)alert returnCode:(int)returnCode contextInfo:(id)sender
+{
+	if (returnCode == NSAlertAlternateReturn)
+		return;
+
 	int key = [[sender selectedItem] tag];
-	[[self document] setKey: key transpose: YES];
+	[[self document] setKey:key transpose:returnCode==NSAlertDefaultReturn];
 	fNeedsRecalc = kRecalc;
 	[self setNeedsDisplay: YES];	
 }