With the seemingly inexorable increase in the use of devices designed to access the internet for an ever increasing series of applications, there is a constant need for data storage technologies with higher densities, non-volatility and lower power consumption.3 Single-phase, room temperature magnetoelectric multiferroic materials are of considerable interest for such applications.4 The unique advantage of these advanced materials is that not only could they find application in high storage density, low-power memory devices that can be electrically written and magnetically read, but also by constructing devices that exploit the presence of both ferroelectric and ferromagnetic states, memory technologies with 4-state logic could be achieved5 - representing a clear improvement over current 2-state logic memory. However, materials that are both multiferroic and magnetoelectric at room temperature are very unusual.6 In this chapter, we review approaches currently under investigation for the fabrication of single phase magnetoelectric multiferroics, from bulk ceramics to those in thin film form. We present an approach of inserting magnetic ions into Aurivillius phase, layer-structured ferroelectric materials, whereby thin films of average composition Bi6Ti2.8Fe1.52Mn0.68O18 demonstrate room temperature ferroelectricity, ferromagnetism and magnetoelectric coupling.2 We discuss the importance of careful microstructural analysis of the materials and the application of a statistical model to determine a confidence level that the observed effects are from genuine single-phase magnetoelectric multiferroics and do not originate from unobserved second phase ferromagnetic inclusions.