In this chapter, we dwell on some mixture design settings and present the underlying optimal designs. The purpose is to acquaint the readers with a variety of interesting and nonstandard areas of mixture designs. The chapter is divided into two parts. In Part A, we cover robust mixture designs and optimality in Scheffé and D–W models with random regression coefficients. In Part B, we discuss mixture–amount model due to Pal and Mandal (Comm Statist Theo Meth 41:665–673, 2012a), multi-response mixture models and mixture designs in blocks. We present the results already available and also some recent findings. © 2014, Springer India.