diff --git a/lib/odata-query-provider.ts b/lib/odata-query-provider.ts
index ebbe849..273a4f9 100644
--- a/lib/odata-query-provider.ts
+++ b/lib/odata-query-provider.ts
@@ -64,28 +64,28 @@ export class ODataQueryProvider implements IQueryProvider {
                 const sel = e.args[1] ? this.handlePartArg(e.args[1]) : null;
 
                 const path = exp.split('/');
-                let ec = es[path[0]] || (es[path[0]] = { children: { } });
+                let ec = es[path[0]] || (es[path[0]] = { children: {} });
 
                 path.slice(1).forEach(p => {
-                    ec = ec.children[p] || (ec.children[p] = { children: { } });
+                    ec = ec.children[p] || (ec.children[p] = { children: {} });
                 });
 
                 ec.select = sel;
             });
 
-            queryParams.push({ key: '$expand', value: expands.join(',') });
+            queryParams.push({ key: '$expand', value: walkExpands(es) });
         }
 
         if (orders.length) {
             const value = orders.map(o => {
                 const v = this.handlePartArg(o.args[0]);
-                return o.type.endsWith('Descending') ? (v + ' desc') : v;
+                return ~descFuncs.indexOf(o.type) ? (v + ' desc') : v;
             }).join(',');
             queryParams.push({ key: '$orderby', value });
         }
 
         for (var p in params) {
-            queryParams.push({ key: '$' + p.replace('where', 'filter').toLowerCase(), value: this.handlePartArg(params[p]) });
+            queryParams.push({ key: '$' + p.replace('where', 'filter'), value: this.handlePartArg(params[p]) });
         }
 
         return this.requestProvider.request<TResult>(queryParams, options);
@@ -98,6 +98,11 @@ export class ODataQueryProvider implements IQueryProvider {
             : this.expToStr(arg.exp, arg.scopes, arg.exp.type === ExpressionType.Func ? (arg.exp as FuncExpression).parameters : [])
     }
 
+    handleExp(exp: Expression, scopes: any[]) {
+        this.rootLambda = true;
+        return this.expToStr(exp, scopes, exp.type === ExpressionType.Func ? (exp as FuncExpression).parameters : [])
+    }
+
     expToStr(exp: Expression, scopes: any[], parameters: string[]): string {
         switch (exp.type) {
             case ExpressionType.Literal:
@@ -193,11 +198,15 @@ export class ODataQueryProvider implements IQueryProvider {
         if (callee.type !== ExpressionType.Member && callee.type !== ExpressionType.Variable)
             throw new Error(`Invalid function call ${this.expToStr(exp.callee, scopes, parameters)}`);
 
-        let args = exp.args.map(a => this.expToStr(a, scopes, parameters)).join(', ');
+        let args: string;
         if (callee.type === ExpressionType.Member) {
             const member = callee as MemberExpression;
             const ownerStr = this.expToStr(member.owner, scopes, parameters);
 
+            if (member.name === '$expand')
+                return ownerStr + '/' + this.handleExp(exp.args[0], scopes);
+
+            args = exp.args.map(a => this.expToStr(a, scopes, parameters)).join(', ');
             // handle Math functions
             if (~mathFuncs.indexOf(callee.name) && ownerStr === 'Math')
                 return `${callee.name}(${args})`;
@@ -208,9 +217,12 @@ export class ODataQueryProvider implements IQueryProvider {
             if (callee.name === 'any' || callee.name === 'all')
                 return `${ownerStr}/${callee.name}(${args})`;
 
-            // other supported functions takes owner as the first argument`
+            // other supported functions takes owner as the first argument
             args = args ? `${ownerStr}, ${args}` : ownerStr;
         }
+        else {
+            args = exp.args.map(a => this.expToStr(a, scopes, parameters)).join(', ');
+        }
 
         const oDataFunc = functions[callee.name] || callee.name;
         return `${oDataFunc}(${args})`;
@@ -285,4 +297,15 @@ const functions = {
 type ExpandContainer = { select?: string, children: ExpandCollection };
 type ExpandCollection = { [expand: string]: ExpandContainer };
 
-// TODO: multi navigation expand desteği için diziye $expand extension metodu. callToStr işlerken $expand için metod adı yerine owner/metod dön!
\ No newline at end of file
+function walkExpands(e: ExpandCollection) {
+    const expStrs = [];
+    for (const p in e) {
+        const exp = e[p];
+        let childStr = walkExpands(exp.children);
+        const expStr = exp.select
+            ? `${p}(${childStr ? `$expand=${childStr},` : ''}$select=${exp.select})`
+            : childStr ? `${p}/${childStr}` : p;
+        expStrs.push(expStr);
+    }
+    return expStrs.join(',');
+}
diff --git a/lib/odata-query.ts b/lib/odata-query.ts
index 7f29543..b6c02e3 100644
--- a/lib/odata-query.ts
+++ b/lib/odata-query.ts
@@ -1,5 +1,5 @@
 import { 
-    IQueryProvider, IQueryPart, Predicate, Func1, Func2, IQueryBase, 
+    IQueryProvider, IQueryPart, Predicate, Func1, IQueryBase, 
     InlineCountInfo, QueryPart, PartArgument, AjaxOptions, AjaxFuncs 
 } from "jinqu";
 
@@ -44,7 +44,7 @@ export class ODataQuery<T> implements IODataQuery<T> {
         return this.create(QueryPart.select(selector, scopes));
     }
 
-    expand<TNav>(navigationSelector: Func2<T, TNav>, selector?: Func2<TNav, any>, ...scopes): IODataQuery<T> {
+    expand<TNav>(navigationSelector: Func1<T, TNav[] | TNav>, selector?: Func1<TNav, any>, ...scopes): IODataQuery<T> {
         return this.create(createExpandPart(navigationSelector, selector, scopes));
     }
 
@@ -71,7 +71,7 @@ export interface IODataQuery<T> extends IQueryBase {
     orderBy(keySelector: Func1<T>, ...scopes): IOrderedODataQuery<T>;
     orderByDescending(keySelector: Func1<T>, ...scopes): IOrderedODataQuery<T>;
     select<TResult = any>(selector: Func1<T, TResult>, ...scopes): IODataQuery<T>;
-    expand<TNav>(navigationSelector: Func2<T, TNav>, selector?: Func2<TNav, any>, ...scopes): IODataQuery<T>;
+    expand<TNav>(navigationSelector: Func1<T, TNav[] | TNav>, selector?: Func1<TNav, any>, ...scopes): IODataQuery<T>;
     skip(count: number): IODataQuery<T>;
     top(count: number): IODataQuery<T>;
     toArrayAsync(): PromiseLike<T[] & InlineCountInfo>;
@@ -82,7 +82,7 @@ export interface IOrderedODataQuery<T> extends IODataQuery<T> {
     thenByDescending(keySelector: Func1<T>, ...scopes): IOrderedODataQuery<T>;
 }
 
-export function createExpandPart<T, TNav>(navigationSelector: Func2<T, TNav>, selector: Func2<TNav, any>, scopes: any[]) {
+export function createExpandPart<T, TNav>(navigationSelector: Func1<T, TNav[] | TNav>, selector: Func1<TNav, any>, scopes: any[]) {
     const args = [PartArgument.identifier(navigationSelector, scopes)];
     if (selector) {
         args.push(PartArgument.identifier(selector, scopes));
@@ -96,7 +96,7 @@ export const ODataFuncs = {
 
 declare global {
     interface Array<T> {
-        $expand<TNav>(navigationSelector: Func1<T, TNav>, selector?: Func1<TNav, any>): TNav;
+        $expand<TNav>(navigationSelector: Func1<T, TNav>): TNav;
     }
 }
 
diff --git a/test/fixture.ts b/test/fixture.ts
index 279a904..23a82cf 100644
--- a/test/fixture.ts
+++ b/test/fixture.ts
@@ -11,9 +11,12 @@ export class MockRequestProvider implements IAjaxProvider {
     }
 }
 
-export class Country {}
+export class Country {
+    name: string;
+}
 
 export class City {
+    name: string;
     country: Country;
 }
 
diff --git a/test/service.spec.ts b/test/service.spec.ts
index 89a6286..e445b7b 100644
--- a/test/service.spec.ts
+++ b/test/service.spec.ts
@@ -2,7 +2,7 @@ import { expect } from 'chai';
 import 'mocha';
 import chai = require('chai');
 import chaiAsPromised = require('chai-as-promised');
-import { CompanyService, MockRequestProvider } from './fixture';
+import { CompanyService, MockRequestProvider, Address } from './fixture';
 
 chai.use(chaiAsPromised);
 
@@ -30,4 +30,79 @@ describe('Service tests', () => {
         expect(prm).property('key').to.equal('$orderby');
         expect(prm).property('value').to.equal('id,name desc');
     });
-});
+
+    it('should create expand with multi level', () => {
+        const query = service.companies().expand(c => c.addresses.$expand(a => a.city).country);
+        expect(query.toArrayAsync()).to.be.fulfilled.and.eventually.be.null;
+        expect(provider).property('options').property('params').to.have.length(1);
+
+        const prm = provider.options.params[0];
+        expect(prm).property('key').to.equal('$expand');
+        expect(prm).property('value').to.equal('addresses/city/country');
+    });
+
+    it('should create expand with multi level using strings 1', () => {
+        const query = service.companies().expand('addresses.city.country');
+        expect(query.toArrayAsync()).to.be.fulfilled.and.eventually.be.null;
+        expect(provider).property('options').property('params').to.have.length(1);
+
+        const prm = provider.options.params[0];
+        expect(prm).property('key').to.equal('$expand');
+        expect(prm).property('value').to.equal('addresses/city/country');
+    });
+
+    it('should create expand with multi level using strings 2', () => {
+        const query = service.companies().expand('c => addresses.city.country');
+        expect(query.toArrayAsync()).to.be.fulfilled.and.eventually.be.null;
+        expect(provider).property('options').property('params').to.have.length(1);
+
+        const prm = provider.options.params[0];
+        expect(prm).property('key').to.equal('$expand');
+        expect(prm).property('value').to.equal('addresses/city/country');
+    });
+
+    it('should create expand with multi level using strings 3', () => {
+        const query = service.companies().expand('c => c.addresses.$expand(a => a.city).country');
+        expect(query.toArrayAsync()).to.be.fulfilled.and.eventually.be.null;
+        expect(provider).property('options').property('params').to.have.length(1);
+
+        const prm = provider.options.params[0];
+        expect(prm).property('key').to.equal('$expand');
+        expect(prm).property('value').to.equal('addresses/city/country');
+    });
+
+    it('should create expand with multi level with explicit calls', () => {
+        const query = service.companies().expand(c => c.addresses)
+            .expand(c => c.addresses.$expand(a => a.city))
+            .expand(c => c.addresses.$expand(a => a.city).country);
+        expect(query.toArrayAsync()).to.be.fulfilled.and.eventually.be.null;
+        expect(provider).property('options').property('params').to.have.length(1);
+
+        const prm = provider.options.params[0];
+        expect(prm).property('key').to.equal('$expand');
+        expect(prm).property('value').to.equal('addresses/city/country');
+    });
+
+    it('should create expand with multi level with explicit calls and selects', () => {
+        const query = service.companies().expand(c => c.addresses, a => a.city)
+            .expand(c => c.addresses.$expand(a => a.city), c => c.country)
+            .expand(c => c.addresses.$expand(a => a.city).country, c => c.name);
+        expect(query.toArrayAsync()).to.be.fulfilled.and.eventually.be.null;
+        expect(provider).property('options').property('params').to.have.length(1);
+
+        const prm = provider.options.params[0];
+        expect(prm).property('key').to.equal('$expand');
+        expect(prm).property('value').to.equal('addresses($expand=city($expand=country($select=name),$select=country),$select=city)');
+    });
+
+    it('should create expand with multi level with explicit calls and mixed selects', () => {
+        const query = service.companies().expand(c => c.addresses, a => a.city)
+            .expand(c => c.addresses.$expand(a => a.city))
+            .expand(c => c.addresses.$expand(a => a.city).country, c => c.name);
+        expect(query.toArrayAsync()).to.be.fulfilled.and.eventually.be.null;
+        expect(provider).property('options').property('params').to.have.length(1);
+
+        const prm = provider.options.params[0];
+        expect(prm).property('key').to.equal('$expand');
+        expect(prm).property('value').to.equal('addresses($expand=city/country($select=name),$select=city)');
+    });});