Plate/panels are the main load bearing components in many structural applications. Such structures are frequently appended with beams/ribs/stiffeners to achieve enhanced strength and weight optimization and referred as stiffened plates/shells. So the analysis of such stiffened structures is of practical importance. Because of unavailability of robust analytical model for analysis of such structures, use of computer-based numerical method like the Finite Element (FE) method seems to be the only feasible option. The present book sketches an overview on the existing state of art for FE analysis of such stiffened plates. Further, a more efficient, robust and simple stiffened plate finite element model is developed and its accuracy and efficiency is demonstrated for analysis of laminated composite and functionally graded stiffened plates of different shape and varying stiffener configuration. A simple and efficient semi refined higher-order sheat deformation theory (SRHSDT7) and a novel least square of error (LSE) method of accurate transverse stress recovery technique for laminated composites are presented. The book may serve as a benchmark on FE analysis of stiffened plates in future.