Oliver's inheritance for themselves. Nancy pretends to be Oliver's sister by putting on middle class clothes in order to get Oliver back to Fagin. Clothes as a means of identifying social class are important. Oliver is stripped of his clothes and pout into pauper clothes. If I were writing a thesis for a paper on this work, I would consider looking at the outward representations of class and status as displayed by clothes and manner of speaking, and the way that these "disguises" can and are used to meet individual desires.

Dickens, in fact, uses this theme as a means of satirizing class structure in Victorian England. You could even gop on to look at other class representations that are symbolized by dress, such as the way in which the Fagin boys almost worship handkerchiefs which they like to steal. These are symbols of affluence. If you carry a handkerchief, you are assumed to be a member of the upper class. If you wear the clothes of a workhouse person, you are seen as a pauper. Again, this is a way Dickens uses outside appearances as a means of denoting class differences from the perspective that people are viewed by society and judged by society by the clothes that they wear.

If you have read any of Dickens's other works or researched this author, you may, then, be familiar with a prevailing social concern of his:  the dehumanizing effects of crime.  Certainly these effects are evinced in the characters of Oliver Twist.  Now, if you wish to compose a thesis on this topic, you may wish to limit your examination to one character if your assignment is an essay.  However, if your assignment is a paper, then you will want to analyze several characters.

Oliver Twist is a narrative in which the most depraved villains preside, with the heinous Fagin controlling the others.  That he loses all humanity is apparent throughout the novel, most strikingly at the end when, incarcerated and alone in his depravity, Fagin loses his mind. As a metaphor of this transformation, the turnkey asks him,

"Fagin, Fagin! Are you a man?"

"I shan't be one long," he replied, looking up with a face retaining no human expression but rage and terror....

Another character, the murderous bully Sikes, evolves throughout the novel into an absolute monster.  Under his control, poor Nancy struggles to retain her humanity, regaining it in her solicitous acts on behalf of Oliver, but falling victim to the band of criminals who will not release her.  In contrast to Oliver, his half brother degenerates spiritually until his final end. For a time, Oliver even suffers some dehumanization and he worries that he will never be believed or treated fairly even if he escapes the evil band of thieves who have captured him. 

I assume from your question that you yourself need to design an essay question based on this novel and need to construct a thesis statement to answer it. Whenever you are given an assignment like this it is very important to start off by focusing either on a character or a theme that is present in the novel and then using that to construct a thesis statement. One element of the novel that is very clear is the way in which Dickens presents us with characters that, with one exception, fall very neatly into one of two categories: good or evil. Of course, it is Nancy who is the exception. Oliver in particular is an excellent example of a character who remains uncorrupted in spite of the company he is forced to keep and the activities he is obliged to engage in. Therefore, you might like to use these ideas as the basis for your essay. A good thesis statement would be:

Oliver Twist is a character that maintains his goodness in spite of his circumstances and situation in life.

This would allow you to examine his character, which is of course a flat character, because he does not really develop or change, in the context of the novel and what happens to him.

A good place to start if you are having to come up with a thesis on a novel is thinking through the themes that are presented through the action, plot and characters and then using one of those themes to create a thesis. There are certainly plenty of themes in this great novel by Dickens, and I have included a link to the themes section on enotes below.

However, one of my favourite themes from this novel, and, I think, the most apparent, is that of Good and Evil and how they are presented in the novel. Clearly the character who is presented as being most "good" is Oliver, and this is worthy of some analysis. He seems to remain completely incorruptible in spite of the range of hideously evil characters that surround him and try to pull him down. Yet a key criticism some people have is that this is at the cost of his development as a proper character. On the whole throughout the novel he is passive and is led easily by other characters.

Note too how other characters are shown as "evil" in spite of the social positions they hold that should make them "good." Mr. Beadle is a key example of this. The only character in the novel that seems to blend the opposing states of good and evil is poor Nancy, who appears to be unlike the rest in her desire to do good and look after Oliver, but at the same time recognising her "evil" background.

I think there should be ample material to write an essay on this theme. Perhaps a thesis you could use would be: "Characters in this novel are either presented as Good or Evil." This would allow you space to discuss Nancy and her presentation. Good luck!

An essay on Oliver Twist could focus on the theme of social justice in Victorian England.

When writing an essay on Oliver Twist, there are many places to start. You can write about a theme, trace a character’s development, or describe the reasons for the book’s popularity today. You could also write about how the author’s life impacted the book.

The theme of social justice in Victorian England is a good topic because Dickens felt strongly about the conditions of the poor. Social justice is the idea that everyone deserves a chance, and no one should be oppressed. Dickens believed that the Poor Law was oppressive. The Poor Law created the workhouses that are so badly depicted in Oliver Twist. When young Oliver is born in the workhouse, he barely survives.

Although I am not disposed to maintain that the being born in a workhouse, is in itself the most fortunate and enviable circumstance that can possibly befall a human being, I do mean to say that in this particular instance, it was the best thing for Oliver Twist that could by possibility have occurred. (ch 1)

Although the book is entertainment, Dickens had a dual purpose in writing it. He wanted people to sympathize with young Oliver, and feel badly about the system. Dickens understood that the poor were suffering, and poor children were either dying or becoming criminals. So he wrote a story about a boy who almost became a criminal, and certainly came into contact with many others who did. Dickens depicts robbers and prostitutes, and takes pains to establish that they are in their situation because the system has failed them.