One of the most recent trends in materials research, and one of the most promising magnetoelectricmagnetoelectricmagnetoelectric (ME) couplingscouplings, is that of the thin-film devices, which provides a novel means of manipulating magnetic characteristics by applying electric fields and vice versa manipulating electric polarizationelectric polarizationelectric polarization by applying magnetic stimuli. The ability of ST to enable both functions is particularly relevant in the context of developing novel applications such as spintronicsspintronicsspintronics, ultra-sensitive sensors, and low-power non-volatile memory devices. Thin-film multiferroicsmultiferroicsmultiferroics, as opposed to their bulk counterpart, have much higher tunability due to effects including reduced dimensionality, lattice strain, interface engineering, and size confinement. These characteristics not only enhance the ME effect, but also represent new opportunities to investigate fundamental physical mechanisms at the nanoscalenanoscalenanoscale. The goal of this chapter is to overview the basic ideas and mechanisms behind ME couplingcouplingcoupling in thin films, from single-phase multiferroics to designed composite and heterostructuresheterostructuresheterostructures. Particular attention is paid to the role of strain-driven, charge-driven, and interface exchange interactions in dictating the strength and stability of ME coupling. The chapter also describes some of the pulsed laser deposition, molecular beam epitaxy, sol–gel processes and other thin-film deposition techniques, and sophistication in characterizing ferroelectricferroelectricferroelectric and magnetic responses. Recent experimental advances and technological demonstrations are in focus, in an attempt to show the trends of what thin-film architectures could be pushing the limits of ME research to. Toward the end of the chapter, the reader should have a complete picture of the role what thin films play as a powerful platform not only to discover new physics, but also an opportunity to design multifunctional devices that will pave the way for the future of electronics and spintronics.