The mixed alkali effect is a well-known phenomenon whereby combining two alkalis in a ternary glass system can produce physical properties which can be superior to, but cannot be predicted from, those of the binary glasses. This effect has also been observed in alkali-alkaline earth (A-B) silicate systems, where changing both the relative amounts of two ions and the type of ions added to the glass can result in a non-linear variation in physical properties. In this study we propose to investigate the effect of varying the ionic radius ratio of alkali : alkaline earth ions on the structure of a series of A-B silicate glasses to determine the short- and intermediate-range ordering. The understanding that these results shall generate will aid our group, and others, engaged in the development of new, improved technical glasses with enhanced physical properties.