diff --git a/crates/oxide_compiler/src/compiler.rs b/crates/oxide_compiler/src/compiler.rs
index 05e304da..e1d4860b 100644
--- a/crates/oxide_compiler/src/compiler.rs
+++ b/crates/oxide_compiler/src/compiler.rs
@@ -151,15 +151,23 @@ impl Compiler {
         ctx.max_regs = ctx.max_regs.max(1);
         ctx.reset_regs();
 
-        let mut last_result = 0u8;
+        let mut last_result: Option<u8> = None;
         for stmt in &program.body {
             if let Some(r) = self.emit_statement(stmt, &mut ctx)? {
-                last_result = r;
+                last_result = Some(r);
             }
         }
 
-        if last_result != 0 {
-            ctx.emit(opcode::encode(OpCode::LOAD_VAR, 0, last_result, 0));
+        if let Some(r) = last_result {
+            ctx.emit(opcode::encode(OpCode::LOAD_VAR, 0, r, 0));
+        } else {
+            let undef_idx = ctx.add_constant(Constant::Undefined);
+            ctx.emit(opcode::encode(
+                OpCode::LOAD_CONST,
+                0,
+                (undef_idx & 0xFF) as u8,
+                ((undef_idx >> 8) & 0xFF) as u8,
+            ));
         }
         ctx.emit(opcode::encode(OpCode::HALT, 0, 0, 0));
 
diff --git a/crates/oxide_vm/src/vm.rs b/crates/oxide_vm/src/vm.rs
index 2d3fd2a9..e2101879 100644
--- a/crates/oxide_vm/src/vm.rs
+++ b/crates/oxide_vm/src/vm.rs
@@ -546,6 +546,21 @@ impl Vm {
                     self.regs[rd] = JsValue::bool(found);
                 }
 
+                OpCode::NOT => {
+                    let cond = coercion::to_boolean(self.regs[a]);
+                    self.regs[rd] = JsValue::bool(!cond);
+                }
+
+                OpCode::AND => {
+                    let cond = coercion::to_boolean(self.regs[a]);
+                    self.regs[rd] = if cond { self.regs[b] } else { self.regs[a] };
+                }
+
+                OpCode::OR => {
+                    let cond = coercion::to_boolean(self.regs[a]);
+                    self.regs[rd] = if cond { self.regs[a] } else { self.regs[b] };
+                }
+
                 _ => {
                     if !op.is_implemented() {
                         return Ok(JsValue::undefined());
diff --git a/crates/oxide_vm/tests/vm_tests.rs b/crates/oxide_vm/tests/vm_tests.rs
index 1ffd831b..3bf3bb1e 100644
--- a/crates/oxide_vm/tests/vm_tests.rs
+++ b/crates/oxide_vm/tests/vm_tests.rs
@@ -165,3 +165,169 @@ fn eval_multi_stmt_last_value() {
 fn eval_var_declaration() {
     assert_eq!(eval("var x = 42"), "42");
 }
+
+#[test]
+fn eval_if_true() {
+    assert_eq!(eval("if (true) { 1 } else { 2 }"), "1");
+}
+
+#[test]
+fn eval_if_false() {
+    assert_eq!(eval("if (false) { 1 } else { 2 }"), "2");
+}
+
+#[test]
+fn eval_if_without_else_true() {
+    assert_eq!(eval("if (true) { 42 }"), "42");
+}
+
+#[test]
+fn eval_if_without_else_false() {
+    assert_eq!(eval("if (false) { 42 }"), "undefined");
+}
+
+#[test]
+fn eval_dangling_else() {
+    assert_eq!(eval("if (true) { if (false) { 1 } else { 2 } }"), "2");
+}
+
+#[test]
+fn eval_while_zero_iterations() {
+    assert_eq!(eval("var x = 0; while (false) { x = 1; } x"), "0");
+}
+
+#[test]
+fn eval_while_multi_iterations() {
+    assert_eq!(eval("var i = 0; while (i < 3) { i = i + 1; } i"), "3");
+}
+
+#[test]
+fn eval_while_result_undefined() {
+    assert_eq!(eval("while (false) { 1; }"), "undefined");
+}
+
+#[test]
+fn eval_for_basic() {
+    assert_eq!(
+        eval("var r = 0; for (i = 0; i < 3; i = i + 1) { r = r + i; } r"),
+        "3"
+    );
+}
+
+#[test]
+fn eval_for_no_test() {
+    assert_eq!(
+        eval("var r = 0; for (i = 0; ; i = i + 1) { if (i >= 3) { break; } r = r + i; } r"),
+        "3"
+    );
+}
+
+#[test]
+fn eval_for_no_init_update() {
+    assert_eq!(eval("var i = 0; for (; i < 3; ) { i = i + 1; } i"), "3");
+}
+
+#[test]
+fn eval_ternary_true() {
+    assert_eq!(eval("true ? 1 : 2"), "1");
+}
+
+#[test]
+fn eval_ternary_false() {
+    assert_eq!(eval("false ? 1 : 2"), "2");
+}
+
+#[test]
+fn eval_ternary_nested() {
+    assert_eq!(eval("true ? (false ? 1 : 2) : 3"), "2");
+}
+
+#[test]
+fn eval_not_true() {
+    assert_eq!(eval("!true"), "false");
+}
+
+#[test]
+fn eval_not_false() {
+    assert_eq!(eval("!false"), "true");
+}
+
+#[test]
+fn eval_not_zero() {
+    assert_eq!(eval("!0"), "true");
+}
+
+#[test]
+fn eval_not_string() {
+    assert_eq!(eval("!'hello'"), "false");
+}
+
+#[test]
+fn eval_and_short_circuit() {
+    assert_eq!(eval("var x = 0; false && (x = 5); x"), "0");
+}
+
+#[test]
+fn eval_and_truthy() {
+    assert_eq!(eval("1 && 2"), "2");
+}
+
+#[test]
+fn eval_and_falsy_first() {
+    assert_eq!(eval("0 && 2"), "0");
+}
+
+#[test]
+fn eval_or_short_circuit() {
+    assert_eq!(eval("var x = 0; true || (x = 5); x"), "0");
+}
+
+#[test]
+fn eval_or_truthy_first() {
+    assert_eq!(eval("1 || 2"), "1");
+}
+
+#[test]
+fn eval_or_falsy_both() {
+    assert_eq!(eval("0 || false"), "false");
+}
+
+#[test]
+fn eval_break_in_while() {
+    assert_eq!(
+        eval("var i = 0; while (true) { i = i + 1; if (i >= 3) { break; } } i"),
+        "3"
+    );
+}
+
+#[test]
+fn eval_continue_in_while() {
+    assert_eq!(
+        eval("var i = 0; var r = 0; while (i < 5) { i = i + 1; if (i == 3) { continue; } r = r + 1; } r"),
+        "4"
+    );
+}
+
+#[test]
+fn eval_break_in_nested_loop() {
+    assert_eq!(
+        eval("var x = 0; while (true) { while (true) { x = x + 1; if (x >= 3) { break; } } break; } x"),
+        "3"
+    );
+}
+
+#[test]
+fn eval_break_in_for() {
+    assert_eq!(
+        eval("var r = 0; for (i = 0; i < 10; i = i + 1) { if (i >= 3) { break; } r = r + i; } r"),
+        "3"
+    );
+}
+
+#[test]
+fn eval_control_flow_complex() {
+    assert_eq!(
+        eval("var r = 0; for (i = 0; i < 5; i = i + 1) { if (i == 2) { continue; } r = r + i; } r"),
+        "8"
+    );
+}