It may seem like a trivial protest, but what do you mean by "middle class?" The modern concept of the middle class is one of the Industrial Revolution: the ancient world knew no such thing. With few exceptions people living in antiquity knew one of two stations of life: either they were exceptionally wealthy or not. A "middling farmer," as Hanson likes to rather quaintly say, might be sort of in between fabulous wealth and destitute poverty, but there is political and social baggage attached to the idea of the middle class in modern parlance that doesn't apply to antiquity. In the Roman world the vast majority of people were either poor farmers living on small plots of land (owned or rented) or urban day-workers living a semi-migratory life as they chased work throughout the city. Both groups lived lives of pretty destitute poverty and had to work hard to keep themselves from starvation. While there's such a thing as the plebs media, predominantly made up of skilled workers and shopkeepers who were therefore not day-laborers and could count on a fairly steady source of (relatively small) income, they were not equivalent to our modern middle class--the plebs media were poor, horribly so, they were only very slightly better off than the day-workers who lived on the cusp of starvation. Further, the plebs media was probably composed of mainly freedmen, which complicates any idea of comparison with the modern middle class--the modern middle class is a relatively politically powerful group, and at least in the United States is often thought of as having some sort of distinct "American" identity, which it's hard to get a sense of from looking at the plebs media. Also pointed to often are the equites, as being a class (really a sub-group of the plebeian order) of political responsibility and rights between the impoverished portions of the urban and rural plebs and the senatorial class. But the frequent comparison with the middle class there falls down almost immediately when we consider that the equites were those outside the senatorial class with senatorial wealth--and frequently a great deal more. That's not particularly indicative of our idea of the middle class as being people neither particularly wealthy nor abjectly impoverished. Before anything can be said on the question, it needs to be defined more precisely, as "middle class" doesn't have particularly good analogues in the ancient world--depending on how we define the "middle class" we might be looking at some freedman goldsmith plying his trade and only barely able to afford bread or we might be looking at Cicero's friend Atticus, among the wealthiest and most learned men in the Republic and one of the leading members of the equites