Savvy companies know how solid the business case is for hiring, advancing and retaining multicultural women: Worldwide, women already control some $20 trillion in annual consumer spending and that number is expected to climb as high as $28 trillion in the next five years. In the United States, women are equally powerful, making an estimated 85 percent of all consumer decisions.

The bottom line: Diversity in the workplace delivers a better understanding of multicultural markets—and a big competitive advantage.

A quintet of Best Companies for Multicultural Women—American Express, Deloitte, General Mills, Procter & Gamble and Verizon Communications—are the leading the pack when it comes to recruiting, advancing and retaining multicultural women.

American Express partners with other organizations to improve its ability to recruit, retain and advance multicultural women. Case in point: Targeted development programs created with Ascent, the national organization dedicated to advancing multicultural women in the workplace. The New York-based financial services company is also committed to diversity training, using both live and virtual programs. Last year, multicultural women represented nearly one-fifth of its new manager hires and 14 percent of its top earners.

Deloitte, the first and only professional services firm to be chaired by a woman, is determined to help women and multicultural employees advance and created the Breakthrough Leadership Program (BLP) to help them do just that. An elite, eight-month-long program, BLP focuses on the development of high-level career skills. Last year almost 100 managers and senior managers at the New York-based firm enrolled, 41 percent of whom were multicultural women.

General Mills sets impressive diversity goals for itself—and closely tracks its progress. The Minneapolis-based consumer-brand company’s laserlike focus on multicultural metrics means it knows exactly how it’s doing. Take recruiting: For fiscal year 2010, 33.4 percent of its hires are multicultural women, as are 19 percent of its interns. As for advancement, last year 37 percent of the company’s women of color in salaried and other professional positions were promoted or took on new roles.

In 2007, Procter & Gamble’s Corporate Women’s Leadership Team took a hard look at the retention and advancement of multicultural women at the Cincinnati-based consumer products company and came up with ways to do it better, including easier “on-ramp, off-ramp” options. Along with multicultural affinity groups, a “mentor-up” program, and other diversity strategies, these practices have pushed the retention rate for multicultural women here to 95 percent from 92.8 percent in just three years.

Communications firm Verizon Communications walks the walk when it comes to training and education for multicultural women, who represented 30 percent of all employees receiving tuition assistance last year (up to $8,000 annually). What’s more, despite a drop in the size of its workforce, the New York-based company boosted overall spending on tuition assistance in 2008 by $5 million, to a total of $118 million.