How can one write an introduction and conclusion for a cause and effect essay about homelessness?

The body of the essay, which you have written is the most challenging part of an essay.  If you have written this part without having formed a thesis, you will need to re-examine it to be certain that each of your body paragraphs contain a topic sentence that makes a new point. Apparently, these are the 3 causes of which you make mention?

Here, then, is what is contained in the introduction of an essay according to Bailey and Powell's The Practical Writer:

• A motivator, or hook- This is one or more sentences that present a reflection, a question, or a quotation that "hooks," or motivates the reader enough to continue reading the essay.
• The thesis statement - Just as the topic sentence of a paragraph states the main idea of that group of sentences, the thesis statement is a general statement of the main idea of the essay.
• A "blueprint" - This is a short list of the principal points that will be presented in the essay. If the essay is a five-paragraph essay, then 3 points are necessary. These 3 points, then, generate the topic sentences of the central paragraphs.

A thesis statement on homelessness could look something like this:

Over the years, homelessness in the United States has become a serious social problem because of (1st point), (2nd point), and (3rd point).

The conclusion, or last paragraph, is simply a summation of the central paragraphs with a reiteration of the thesis statement. It has two parts:  a reworded thesis statement and what is known as a "clincher"; that is, a finishing sentence that has impact, leaving no doubt in the mind of the reader that the essay is at its end; also, the clincher is a reminder of the motivator. Here is an example of a clincher:

Clearly, that person who sleeps under the viaduct is yet a human being with needs, both psychological and physical.

The conclusion is simply a wrapping up of the writer's main points and their purpose.

See the links below for further assistance. Good luck!

How should an introduction and conclusion be written for a cause and effect essay about homelessness?

The introduction and conclusion should contain a thesis statement that clearly and concisely summarizes your essay.

A thesis statement is supposed to clearly indicate what you are writing to prove in your essay.  Since your essay is a cause and effect essay on homelessness, you must be arguing that the three particular causes were responsible for homelessness.  How can you generalize them to one theme?  For example, let’s say they were all related to the economy.  In that case, your thesis would be that the bad economy caused the homelessness. 

The economic recession has caused an increase in homelessness in America.

If this is your thesis, you can then build an essay around it where you describe how the aspects of the economic slowdown that you describe contributed to the problem.  For example, you could describe how the drastic drop in home values caused an increase in home foreclosures.   As a result, more people were forced out on the streets and unable to afford a new home, especially if they also lost a job.  

In your introduction and conclusion, you want to make your case.  The introduction introduces your argument to the reader in the form of a hook and thesis, and previews your points.  The conclusion restates your thesis and summarizes your points, reminding the reader of your argument and why you made it convincingly.