diff --git a/src/data/transfer_region.rs b/src/data/transfer_region.rs
index 78ae68f..1f21b5e 100644
--- a/src/data/transfer_region.rs
+++ b/src/data/transfer_region.rs
@@ -10,10 +10,34 @@ pub struct TransferRegion<'a> {
     pub source_region: Region, // Even if it is just a point, we don't want corners.
     pub dest_plate: &'a Plate,
     pub dest_region: Region,
-    pub offset: Option<(i8,i8)>,
+    pub interleave_source: Option<(i8,i8)>,
+    pub interleave_dest: Option<(i8,i8)>,
 }
 
 impl TransferRegion<'_> {
+    pub fn get_source_wells(&self) -> Vec<(u8,u8)> {
+        if let Region::Rect(c1, c2) = self.source_region {
+            let mut wells = Vec::<(u8,u8)>::new();
+            let (ul, br) = standardize_rectangle(&c1, &c2);
+            let (interleave_i, interleave_j) = self.interleave_source.unwrap_or((1,1));
+            // NOTE: This will panic if either is 0!
+            // We'll reassign these values (still not mutable) just in case.
+            // This behaviour shouldn't be replicated for destination wells
+            // because a zero step permits pooling.
+            let (interleave_i, interleave_j) = (i8::max(interleave_i, 1), i8::max(interleave_j, 1));
+
+            for i in (ul.0..=br.0).step_by(i8::abs(interleave_i) as usize) {
+                for j in (ul.0..=br.0).step_by(i8::abs(interleave_j) as usize) {
+            // NOTE: It looks like we're ignoring negative interleaves,
+            // because it wouldn't make a difference here---the same
+            // wells will still be involved in the transfer.
+                    wells.push((i,j))
+                }
+            }
+            return wells;
+        } else { panic!("Source region is just a point!") }
+    }
+
     pub fn validate(&self) -> Result<(), String> {
         // Checks if the region does anything suspect
         //
@@ -87,6 +111,14 @@ fn in_region(pt: (u8,u8), r: &Region) -> bool {
     }
 }
 
+fn standardize_rectangle(c1: &(u8,u8), c2: &(u8,u8)) -> ((u8,u8),(u8,u8)) {
+    let upper_left_i = u8::min(c1.0, c2.0);
+    let upper_left_j = u8::min(c1.1, c2.1);
+    let bottom_right_i = u8::max(c1.0, c2.0);
+    let bottom_right_j = u8::max(c1.1, c2.1);
+    return ((upper_left_i,upper_left_j),(bottom_right_i,bottom_right_j));
+}
+
 #[cfg(debug_assertions)]
 use std::fmt;
 
@@ -95,10 +127,11 @@ impl fmt::Display for TransferRegion<'_> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         writeln!(f, "Source Plate:")?;
         let source_dims = self.source_plate.size();
+        let source_wells = self.get_source_wells();
         let mut source_string = String::new();
         for i in 1..=source_dims.0 {
             for j in 1..=source_dims.1 {
-                if in_region((i,j), &self.source_region) {
+                if source_wells.contains(&(i,j)) {
                     source_string.push_str("x")
                 } else {
                     source_string.push_str("o")
diff --git a/src/lib.rs b/src/lib.rs
index c976d85..ec4adf7 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -29,7 +29,9 @@ pub fn plate_test() {
         source_region: transfer_region::Region::Rect((1,1), (6,6)),
         dest_plate: &destination,
         dest_region: transfer_region::Region::Rect((1,1), (6,6)),
-        offset: None
+        interleave_source: Some((2,1)),
+        interleave_dest: None
     };
-    println!("{}", transfer)
+    println!("{}", transfer);
+    println!("{:?}", transfer.get_source_wells());
 }