Each business day, TheStreet.com Ratings compiles a list of the top five stocks in one of five categories -- fast-growth, all-around value, large-cap, mid-cap and small-cap -- based on data from the close of the previous trading session. Today we focus on mid-caps.

These are stocks of companies that have market capitalizations of between $500 million and $10 billion that rank near the top of all stocks rated by our proprietary quantitative model, which looks at more than 60 factors. The stocks must also be followed by at least one financial analyst who posts estimates on the Institutional Brokers' Estimate System. They are ordered by their potential to appreciate.

Note that no provision is made for off-balance-sheet assets such as unrealized appreciation/depreciation of investments, market value of real estate or contingent liabilities that might affect book value. This could be material for some companies with large underfunded pension plans.

DeVry ( DV) is an international higher education company that operates DeVry University, Ross University, Chamberlin College of Nursing and Becker Professional Review. We have rated it a buy since January 2007. DeVry's strengths can be seen in a variety of areas, such as its impressive record of earnings-per-share growth, good cash flow from operations, robust revenue growth and largely solid financial position.

The company reported revenue growth of 21.3% year over year in the first quarter of fiscal 2009. This growth outpaced the industry average of 12.7%, and it also appears to have helped boost EPS, which improved 29.7% when compared to the same quarter last year. Net operating cash flow increased 21% to $96.8 million in the first quarter. DeVry has a very low debt-to-equity ratio of 0.2, which implies that the company has been very successful at managing its debt levels. During September 2008, DeVry completed the acquisition of U.S. Education, the parent company of Apollo College and Western Career College, which operates 17 campus locations in the western United States.

Management stated that DeVry's strong first quarter results were driven by a strategic plan to increase enrollment through improved marketing and recruiting. The acquisition of U.S. Education also helps this strategic plan by allowing DeVry to further diversify its educational offerings. The company is confident that it should be able to continue maximizing shareholder value and achieving long-term growth goals despite a tough economy due to its diversified portfolio. It is important to remember that a quick ratio of 0.7 indicates a potential problem in covering short-term cash needs. In addition, the company shows low profit margins. All the same, we feel that the strengths detailed above are enough to outweigh any potential weaknesses at this time.

New Jersey Resources ( NJR - Get Report) is an energy services holding company that provides retail and wholesale energy services to customers in New Jersey, other states from the Gulf Coast to New England, and Canada. We have rated it a buy since September 2002. This rating is supported by the company's healthy revenue growth, solid stock price performance, compelling net income growth, and impressive record of EPS growth.

For the fourth quarter of fiscal 2008, the company reported revenue growth of 40.1% year over year, which outpaced the industry average of 22.6%. Revenue growth appears to have helped boost EPS, which rose significantly from a loss of 91 cents per share in the fourth quarter of fiscal 2007 to a profit of $1.86 in the most recent quarter. Net income surged 305.1% when compared to the same quarter a year ago. In addition, the company announced that its Board of Directors recently approved a 10.7% dividend increase, bringing the quarterly dividend rate to 31 cents per share. The company has paid quarterly dividends continuously since it began in 1952.

Looking ahead to fiscal 2009, New Jersey Resources forecasts net financial earnings in the range of $2.30 to $2.40 per basic share. Approximately 30% to 40% of those earnings are expected to come from the company's wholesale energy services subsidiary, NJR Energy Services. The company shows low profit margins, but we feel that its strengths outweigh any potential weakness at this time. Strong earnings growth has helped the stock price rise over the past year, and the stock should see more upside potential unless a broad bear market prevails.

California Water Service Group ( CWT - Get Report) is a holding company that provides water utility and other related services in California, Washington, New Mexico and Hawaii through its subsidiaries. We upgraded it to a buy in August 2008. Our rating is based on a number of company strengths, including its revenue and net income growth, impressive record of EPS growth, expanding profit margins and good cash flow from operations.

For the third quarter of fiscal 2008, the company's revenue rose 15.7% year over year. Revenue growth appears to have helped boost EPS, which improved over the past year from 67 cents to $1.06. Net income also increased when compared to the same quarter a year ago, climbing 60.6% from $13.1 million to $22.2 million. We consider the company's gross profit margin of 37.6% to be strong. It has increased from the same quarter of fiscal 2007. In addition, the net profit margin of 16.8% is above that of the industry average. Furthermore, net operating cash flow has increased significantly, rising 86.6% to $48.3 million.

Looking forward, California Water Service Group expects to be able to pursue water efficiency programs in order to benefit ratepayers and reduce overall water demand. Although the company may harbor some minor weaknesses, we fell they are unlikely to have a significant impact on results.

Cubist Pharmaceuticals ( CBST) is a biopharmaceutical company that engages in the research, development and commercialization of pharmaceutical products for the anti-infective market. We upgraded it from a hold to a buy in October 2008. Our rating is supported by a number of strengths, such as its robust revenue growth, solid stock price performance, and expanding profit margins. Growth in net income and EPS also contribute to the company's strengths.

The company reported 40.9% year-over-year revenue growth in the third quarter of fiscal 2008, contributing to an EPS improvement of 37.5%. EPS climbed from 32 cents in the third quarter of fiscal 2008 to 44 cents in the most recent quarter. The company has, in fact, demonstrated a pattern of positive EPS growth over the past two years, and we feel that this trend is likely to continue. Net income also increased in the third quarter, increasing 39.5% from where it was a year ago. Although Cubist's gross profit margin is very high at 79.1%, it has managed to decrease that result compared to the prior year's quarter. In addition, the company's net profit margin of 24.8% compares favorably with the average for the biotechnology industry.

The stock price is not only higher than it was a year ago, but it also outperformed the S&P 500 over the same period of time. Strong earnings growth appears to have been key to this growth, although other factors clearly played a role as well. Although even the best stocks can fall in an overall down market, we feel that this stock still has good upside potential under any other market conditions. Although no company is perfect, we do not currently see any significant weaknesses that are likely to detract from Cubist's generally positive outlook.

Tompkins Financial ( TMP - Get Report) is the corporate parent of three community banks: Tompkins Trust Company, The Bank of Castile and Mahopac National Bank. We have rated it a buy since October 2007 on the basis of its notable return on equity, expanding profit margins, increased in net income and revenue, and solid stock price performance.

For the third quarter of fiscal 2008, the company reported revenue growth of 6.3% year over year. This appears to have helped boost EPS, which rose 15.7% to a record level for the company. EPS was reported as 81 cents for the third quarter, compared to 70 cents in the prior year's quarter. Net income also increased, rising 16.6% from $6.8 million to $7.9 million. Return on equity improved slightly over where it was a year ago, which can be construed as a modest strength for the company. Tompkins' return on equity of 14.1% exceeded the average for the commercial banking industry. The company's stock price has risen over the past year, reflecting earnings growth and other positive factors.

Management stated that the company was fortunate to operate in markets that were not as heavily impacted by the national and global economic crisis as some areas of the country. A focus on long-term results allowed Tompkins to continue to perform well in challenging economic times, allowing the company to grow its business while still avoiding high-profile risky loans and investments. Although the company's stock is currently trading at a premium valuation, we feel that its strengths justify the higher price levels at this time.

Our quantitative rating is based on a variety of historical fundamental and pricing data and represents our opinion of a stock's risk-adjusted performance relative to other stocks.

However, the rating does not incorporate all of the factors that can alter a stock's performance. For example, it doesn't always factor in recent corporate or industry events that could affect the stock price, nor does it include recent technology developments and competitive dynamics that may affect the company.

For those reasons, we believe a rating alone cannot tell the whole story and should be part of an investor's overall research.