“The First 100 Days” is an old political term coined in the days of FDR and used ever since as a bellwether for the effectiveness of a new president. While pundits and politicians have long debated the significance of this benchmark, the concept might be more appropriate for another type of leader: The CEO. 

Last year, more than 50 companies in the S&P 500 replaced their CEOs. From a reputational perspective, the first 100 days is a critical period for the incoming chief. First impressions matter a lot—and both the actions and the tone set by new leaders come under great scrutiny. 

This is the opportune time to lay out priorities, frame the way in which success should be evaluated, and put in place the building blocks to achieve this success. For CEOs of public companies, the urgency is compounded by the fact that, during this time, he or she will need to discuss earnings and business strategy with the financial community for the first time in this new role. 

So how does a new CEO make the most of this 100-day window to build confidence in the future direction of the company? 

1. Lay a strong foundation. Before a plan is articulated, the CEO can take steps to help ensure that employees will be receptive to carrying it out. In the wake of Time Warner’s disappointing merger with AOL, for example, Richard Parsons spent much of his first few months meeting with small groups of employees and assuring them the channels of communication would stay open. His candor helped calm widespread employee unrest and build a mandate for the tough decisions he would make later. 

2. Inspire passion for the cause. Ideally, the strategic priorities set forth by the CEO should be reinforced by a strong, committed leadership team. CEO Howard Schultz, for example, returned to Starbucks in 2008 after an eight-year hiatus to find a company that had lost its luster. His first act was to draw up an agenda to reignite an emotional attachment with customers. As he handed copies of his plan to senior executives, he confronted each one with the question: Are you in, or are you out? The naysayers were pushed toward the exit, while the believers helped Schultz pull off one of the most remarkable corporate turnarounds. 

3. Build a foundation of trust based on candor. To ensure their messages resonate, leaders must quickly build trust outside the office, too. That involves communicating effectively with analysts, investors, government officials, journalists and, of course, the board of directors. A key part of securing sustainable support is setting benchmarks that others can use to measure performance—be it concrete goals that reflect the CEO’s vision and confidence or less tangible aspirations such as increasing transparency—as well as identifying issues that need to be addressed. Candor is critical to building trust. The trick, of course, is not to overpromise. 

4. Consider the symbolism as well as the substance. Early actions can have great symbolic value beyond their concrete business impact. In his first few months as CEO at Intel, Paul Otellini eased doubts about the company’s struggling product line by announcing that Apple would begin using Intel chips for the first time. And when Marissa Mayer joined Yahoo!, she quickly distributed smartphones to employees, offered free meals at the office cafeteria, and ended the company’s work-from-home policy to signal her determination to change Yahoo!’s culture. It quickly became clear to everyone that a different kind of leader had taken the reins. 

5. Be true to yourself. A critical objective for new CEOs is demonstrating what will distinguish them as leaders. CEOs should work to establish personal profiles which are assets for their companies, embodying their values. But they must be authentic. Establishing a style of communications that fits and setting the right tone from the outset will help carry them through the challenges ahead.

No one ever cements his or her legacy in the first 100 days, but the most successful new CEOs make every one of them count. 

Michael Gross is Finsbury’s CEO. He is based in New York City.