diff --git a/mustache/data.odin b/mustache/data.odin
index 3053558..7a0f78e 100644
--- a/mustache/data.odin
+++ b/mustache/data.odin
@@ -155,6 +155,32 @@ is_truthy :: proc(a: any) -> bool {
 	}
 }
 
+call_interp_lambda :: proc(val: any) -> (result: string, ok: bool) {
+	switch v in val {
+	case proc() -> string:
+		return v(), true
+	case proc() -> int:
+		return fmt.tprintf("%d", v()), true
+	case proc() -> bool:
+		return "true" if v() else "false", true
+	case:
+		return "", false
+	}
+}
+
+call_section_lambda :: proc(val: any, text: string) -> (result: string, ok: bool) {
+	switch v in val {
+	case proc(string) -> string:
+		return v(text), true
+	case proc(string) -> int:
+		return fmt.tprintf("%d", v(text)), true
+	case proc(string) -> bool:
+		return "true" if v(text) else "false", true
+	case:
+		return "", false
+	}
+}
+
 // list_info returns element type info, count, and data pointer for a list value.
 // Returns elem_info=nil if the value is not a list.
 list_info :: proc(a: any) -> (elem_info: ^runtime.Type_Info, count: int, data: rawptr) {
diff --git a/mustache/lambda_test.odin b/mustache/lambda_test.odin
new file mode 100644
index 0000000..33d74a1
--- /dev/null
+++ b/mustache/lambda_test.odin
@@ -0,0 +1,147 @@
+#+test
+package mustache
+
+import "core:fmt"
+import "core:testing"
+
+// --- Spec test 1: Interpolation ---
+// A lambda's return value should be interpolated.
+
+Interp_Data :: struct {
+	lambda: proc() -> string,
+	planet: string,
+}
+
+Interp_Data_Int :: struct {
+	lambda: proc() -> int,
+	planet: string,
+}
+
+@(test)
+test_lambda_interpolation :: proc(t: ^testing.T) {
+	data := Interp_Data {
+		lambda = proc() -> string {return "world"},
+	}
+	tpl, _ := parse("Hello, {{lambda}}!", context.temp_allocator)
+	result, _ := render(tpl, data, allocator = context.temp_allocator)
+	testing.expect_value(t, result, "Hello, world!")
+}
+
+// --- Spec test 2: Interpolation - Expansion ---
+// A lambda's return value should be parsed.
+
+@(test)
+test_lambda_interpolation_expansion :: proc(t: ^testing.T) {
+	data := Interp_Data {
+		lambda = proc() -> string {return "{{planet}}"},
+		planet = "world",
+	}
+	tpl, _ := parse("Hello, {{lambda}}!", context.temp_allocator)
+	result, _ := render(tpl, data, allocator = context.temp_allocator)
+	testing.expect_value(t, result, "Hello, world!")
+}
+
+// --- Spec test 4: Interpolation - Multiple Calls ---
+// Interpolated lambdas should not be cached.
+
+counter_lambda :: proc() -> int {
+	@(static) call_count := 0
+	call_count += 1
+	return call_count
+}
+
+@(test)
+test_lambda_interpolation_multiple_calls :: proc(t: ^testing.T) {
+	data := Interp_Data_Int {
+		lambda = counter_lambda,
+	}
+	tpl, _ := parse("{{lambda}} == {{{lambda}}} == {{lambda}}", context.temp_allocator)
+	result, _ := render(tpl, data, allocator = context.temp_allocator)
+	testing.expect_value(t, result, "1 == 2 == 3")
+}
+
+// --- Spec test 5: Escaping ---
+// Lambda results should be appropriately escaped.
+
+@(test)
+test_lambda_escaping :: proc(t: ^testing.T) {
+	data := Interp_Data {
+		lambda = proc() -> string {return ">"},
+	}
+	tpl, _ := parse("<{{lambda}}{{{lambda}}}", context.temp_allocator)
+	result, _ := render(tpl, data, allocator = context.temp_allocator)
+	testing.expect_value(t, result, "<&gt;>")
+}
+
+// --- Spec test 6: Section ---
+// Lambdas used for sections should receive the raw section string.
+
+Section_Data :: struct {
+	lambda: proc(_: string) -> string,
+	x:      string,
+	planet: string,
+}
+
+@(test)
+test_lambda_section :: proc(t: ^testing.T) {
+	data := Section_Data {
+		lambda = proc(text: string) -> string {
+			if text == "{{x}}" {return "yes"} else {return "no"}
+		},
+		x = "Error!",
+	}
+	tpl, _ := parse("<{{#lambda}}{{x}}{{/lambda}}>", context.temp_allocator)
+	result, _ := render(tpl, data, allocator = context.temp_allocator)
+	testing.expect_value(t, result, "<yes>")
+}
+
+// --- Spec test 7: Section - Expansion ---
+// Lambdas used for sections should have their results parsed.
+
+@(test)
+test_lambda_section_expansion :: proc(t: ^testing.T) {
+	data := Section_Data {
+		lambda = proc(text: string) -> string {
+			return fmt.tprintf("%s{{{{planet}}}}%s", text, text)
+		},
+		planet = "Earth",
+	}
+	tpl, _ := parse("<{{#lambda}}-{{/lambda}}>", context.temp_allocator)
+	result, _ := render(tpl, data, allocator = context.temp_allocator)
+	testing.expect_value(t, result, "<-Earth->")
+}
+
+// --- Spec test 9: Section - Multiple Calls ---
+// Lambdas used for sections should not be cached.
+
+@(test)
+test_lambda_section_multiple_calls :: proc(t: ^testing.T) {
+	data := Section_Data {
+		lambda = proc(text: string) -> string {
+			return fmt.tprintf("__%s__", text)
+		},
+	}
+	tpl, _ := parse("{{#lambda}}FILE{{/lambda}} != {{#lambda}}LINE{{/lambda}}", context.temp_allocator)
+	result, _ := render(tpl, data, allocator = context.temp_allocator)
+	testing.expect_value(t, result, "__FILE__ != __LINE__")
+}
+
+// --- Spec test 10: Inverted Section ---
+// Lambdas used for inverted sections should be considered truthy.
+
+Inverted_Data :: struct {
+	lambda: proc(_: string) -> bool,
+	static: string,
+}
+
+@(test)
+test_lambda_inverted_section :: proc(t: ^testing.T) {
+	data := Inverted_Data {
+		lambda = proc(text: string) -> bool {return false},
+		static = "static",
+	}
+	tpl, _ := parse("<{{^lambda}}{{static}}{{/lambda}}>", context.temp_allocator)
+	result, _ := render(tpl, data, allocator = context.temp_allocator)
+	testing.expect_value(t, result, "<>")
+}
+
diff --git a/mustache/mustache.odin b/mustache/mustache.odin
index 9f4a956..7c050d2 100644
--- a/mustache/mustache.odin
+++ b/mustache/mustache.odin
@@ -48,6 +48,7 @@ Node :: struct {
 	indent:      string,
 	first_child: int,
 	child_count: int,
+	content:     string,
 }
 
 // node_span returns the number of flat-array entries a node occupies:
@@ -103,7 +104,7 @@ parse :: proc(
 		return {}, terr
 	}
 
-	tmpl.nodes, err = parse_tokens(tokens[:], allocator)
+	tmpl.nodes, err = parse_tokens(tokens[:], source, allocator)
 	if err != nil {
 		delete(tmpl.nodes)
 		return {}, err
@@ -148,6 +149,7 @@ render :: proc(
 
 parse_tokens :: proc(
 	tokens: []Token,
+	source: string,
 	allocator := context.allocator,
 ) -> (
 	nodes: [dynamic]Node,
@@ -155,7 +157,7 @@ parse_tokens :: proc(
 ) {
 	nodes = make([dynamic]Node, 0, len(tokens), allocator)
 	pos := 0
-	err = parse_section(tokens, &pos, &nodes, "")
+	err = parse_section(tokens, &pos, &nodes, "", source)
 	return
 }
 
@@ -164,6 +166,7 @@ parse_section :: proc(
 	pos: ^int,
 	nodes: ^[dynamic]Node,
 	end_tag: string,
+	source: string,
 ) -> Render_Error {
 	for pos^ < len(tokens) {
 		tok := tokens[pos^]
@@ -187,18 +190,28 @@ parse_section :: proc(
 		case .Section_Open:
 			pos^ += 1
 			idx := len(nodes)
+			content_start := 0
+			if pos^ < len(tokens) { content_start = tokens[pos^].pos }
 			append(nodes, Node{kind = .Section, key = tok.value, first_child = -1})
-			parse_section(tokens, pos, nodes, tok.value) or_return
+			parse_section(tokens, pos, nodes, tok.value, source) or_return
+			close_pos := 0
+			if pos^ - 1 >= 0 && pos^ - 1 < len(tokens) { close_pos = tokens[pos^ - 1].pos }
 			nodes[idx].first_child = idx + 1
 			nodes[idx].child_count = len(nodes) - idx - 1
+			nodes[idx].content = source[content_start:close_pos]
 
 		case .Inverted_Open:
 			pos^ += 1
 			idx := len(nodes)
+			content_start := 0
+			if pos^ < len(tokens) { content_start = tokens[pos^].pos }
 			append(nodes, Node{kind = .Inverted, key = tok.value, first_child = -1})
-			parse_section(tokens, pos, nodes, tok.value) or_return
+			parse_section(tokens, pos, nodes, tok.value, source) or_return
+			close_pos := 0
+			if pos^ - 1 >= 0 && pos^ - 1 < len(tokens) { close_pos = tokens[pos^ - 1].pos }
 			nodes[idx].first_child = idx + 1
 			nodes[idx].child_count = len(nodes) - idx - 1
+			nodes[idx].content = source[content_start:close_pos]
 
 		case .Section_Close:
 			if end_tag != "" && tok.value == end_tag {
@@ -236,7 +249,7 @@ parse_section :: proc(
 				nodes,
 				Node{kind = .Parent, key = tok.value, indent = tok.indent, first_child = -1},
 			)
-			parse_section(tokens, pos, nodes, tok.value) or_return
+			parse_section(tokens, pos, nodes, tok.value, source) or_return
 			nodes[idx].first_child = idx + 1
 			nodes[idx].child_count = len(nodes) - idx - 1
 
@@ -247,7 +260,7 @@ parse_section :: proc(
 				nodes,
 				Node{kind = .Block, key = tok.value, indent = tok.indent, first_child = -1},
 			)
-			parse_section(tokens, pos, nodes, tok.value) or_return
+			parse_section(tokens, pos, nodes, tok.value, source) or_return
 			nodes[idx].first_child = idx + 1
 			nodes[idx].child_count = len(nodes) - idx - 1
 		}
@@ -447,17 +460,42 @@ render_nodes :: proc(
 
 		case .Variable:
 			val := resolve_name(node.key, ctx[:])
-			write_value(b, val, escape = true)
+			if result_str, ok := call_interp_lambda(val); ok {
+				sub_tpl, perr := parse(result_str, context.temp_allocator, context.temp_allocator)
+				if perr == nil {
+					temp: strings.Builder
+					strings.builder_init(&temp, context.temp_allocator)
+					render_nodes(sub_tpl.nodes[:], sub_tpl.nodes[:], ctx, partials, &temp, blocks) or_return
+					write_value(b, strings.to_string(temp), escape = true)
+				}
+			} else {
+				write_value(b, val, escape = true)
+			}
 			i += 1
 
 		case .Unescaped:
 			val := resolve_name(node.key, ctx[:])
-			write_value(b, val, escape = false)
+			if result_str, ok := call_interp_lambda(val); ok {
+				sub_tpl, perr := parse(result_str, context.temp_allocator, context.temp_allocator)
+				if perr == nil {
+					temp: strings.Builder
+					strings.builder_init(&temp, context.temp_allocator)
+					render_nodes(sub_tpl.nodes[:], sub_tpl.nodes[:], ctx, partials, &temp, blocks) or_return
+					write_value(b, strings.to_string(temp), escape = false)
+				}
+			} else {
+				write_value(b, val, escape = false)
+			}
 			i += 1
 
 		case .Section:
 			val := resolve_name(node.key, ctx[:])
-			if is_truthy(val) {
+			if result_str, ok := call_section_lambda(val, node.content); ok {
+				sub_tpl, perr := parse(result_str, context.temp_allocator, context.temp_allocator)
+				if perr == nil {
+					render_nodes(sub_tpl.nodes[:], sub_tpl.nodes[:], ctx, partials, b, blocks) or_return
+				}
+			} else if is_truthy(val) {
 				children := all_nodes[node.first_child:node.first_child + node.child_count]
 				elem_info, count, data := list_info(val)
 				if elem_info != nil {