This article introduces a conceptual reference framework – the Models and Data (MODA) framework – to support a data-centric and model-driven approach for the integration of heterogeneous models and their respective data for the entire life-cycle of socio-technical systems. While MODA was developed to capture emerging socio-technical systems with different model types, it is sufficiently expressive to characterize and generalize existing complex engineering practices and technologies in the system life-cycle, which we demonstrate with thirteen well-known processes, technologies, and systems. We also identify several key research challenges with proposed follow- on studies for realizing MODA. We expect the MODA framework to be used (i) as a guide for educational purposes to clarify roles of models, data sources, and related actions during a wide variety of system life-cycles; (ii) to organize and compare complex engineering processes and technologies to support critical engineering choices involving large landscapes (e.g., smart grid systems); and (iii) to situate existing research approaches or initiate new research agendas to improve the integration of different types of models and data sources (e.g., air quality management, climate change).