After clearing MCTS . you can proceed to MCPD which forms the next level
The different specializations for MCPD are

Professional Developer: Web Developer
* Prerequisite: MCTS: .NET Framework 2.0 Web Applications
* Exam 70-547: PRO: Designing and Developing Web Applications by Using the Microsoft .NET Framework

Professional Developer: Windows Developer
* Prerequisite: MCTS: .NET Framework 2.0 Windows Applications
* Exam 70–548: PRO: Designing and Developing Windows Applications by Using the Microsoft .NET Framework

Professional Developer: Enterprise Applications Developer
* Prerequisite: MCTS: .NET Framework 2.0 Web Applications
* Prerequisite: MCTS: .NET Framework 2.0 Windows Applications
* Prerequisite: MCTS: .NET Framework 2.0 Distributed Applications
* Exam 70–549: PRO: Designing and Developing Enterprise Applications by Using the Microsoft .NET Framework

NOTE:
To write the first two specializations MCTS in the particualar stream is necesary.
To write the third specialization(Enterprise Application Developer) ,MCTS in all the streams are necessary.