To provide a practical solution to the challenging problems of MPSoC designs, we have proposed a new framework for MPSoC designs which we call the tightly-coupled thread (TCT) model. Our TCT model provides a drastically simple programming model on C language which allows designers to specify system partitioning directly on the reference C code without having to deal with the time-consuming task of modeling the interactions between partitioned concurrent processes. Our TCT compiler handles automatic insertion of inter-processor communications and generates the concurrent executable model which can model a wide variety of parallel processing styles such as functional pipelining and task parallelism as well as their combinations. Our TCT trace scheduler is used to evaluate the system performance and characteristics such as execution time and communication bandwidth. Our TCT framework was also verified on a prototype MPSoC where a custom-designed processor array consisting of 6 processing elements was embedded inside the AMBA-based SoC with a very efficient processor communication interconnect which only require 2 to 6 setup cycles and 4-byte/cycle burst transfer.