In many ways, Teasdale's poem talks about the masks that people wear in order to conceal their own sense of self from others.  The insight that come across in Teasdale's poem is one of a masquerade, where people don different masks in order to fully conceal their pain and their own sense of shame and embarrassment that lies at the heart of their being.  The speaker, presumably Teasdale, is arguing that the modern construction of progress and social conformity is one where there is a sense hiding and concealment in consciousness.  This permeates in how people relate to one another:

Do you know how much you tell
In the meeting of our eyes
How ashamed I am, and sad
To have pierced your poor disguise?

In this stanza, the "disguise" can conceal one's own sense of shame, guilt, doubt, and insecurity that the speaker feels is hidden underneath the "city's broken roar." This hidden reality is what keeps individuals sustaining through the rigors of daily life.  Yet, the speaker does not exclude herself from this condition, as the last line reflects that the "meeting" of eyes between the speaker and the other people is a reflection that they see through her mask and she sees through theirs.  In this, there is a realization that a hidden reality is how all reality operates.  Teasdale once wrote that she was "a flower amid the toiling world."  Perhaps, it is this condition that is being hidden behind this element of "disguise."