Design of modern aircraft relies heavily on modeling and simulation for reducing cost and improving performance. However, the complexity of aircraft architectures requires accurate modeling of dynamic components across many subsystems. Integrated power and thermal modeling necessitates dynamic simulations of liquid, air, and two-phase fluids within vapor cycle system components, air cycle machine and propulsion components, hydraulic components, and more while heat generation of many on-board electrical components must also be precisely calculated as well. Integration of these highly complex subsystems may result in simulations which are too computationally expensive for quickly modeling extensive variations of aircraft architecture, or will require simulations with reduced accuracy in order to provide computationally inexpensive models. As such, a need for software toolsets with the ability to model complex aircraft architectures with accurate calculations while maintaining high computational speeds is apparent. This paper details the development of the ATTMOSphere toolset which enables modeling of electrical, mechanical, thermal, fluid flow and heat transfer across a range of components applicable to integrated power and thermal systems. Graphical user interfaces provide user-friendly parameterization of components, as well as sizing of many of the available components. All ATTMOSphere components operate within universal mechanical, thermal, electrical, and fluid domains allowing for seamless integration of components across many architectures, providing end-users with the ability to simultaneously model vapor cycle systems, air cycle systems, pumped refrigeration systems, and other power and thermal systems along with their interactions with parallel subsystems. This paper provides details of the components developed in ATTMOSphere along with examples of user interfaces and design codes. Demonstration models are presented to illustrate the integrated dynamic analysis capability of the toolset.