It’s far easier to persuade people when they trust your expertise. But proclaiming, “I’m an expert here!” is likely to rub them the wrong way. So, whether you’re trying to get a client to sign on with your company or convince colleagues to buy into your idea, how can you establish your authority — without sounding arrogant or like a know-it-all? One way is to bring in someone they trust to endorse your expertise. You may ask a senior colleague to speak up about your authority on the subject matter at hand. Or, you can even reference your relationship with a third party whom your employees trust and admire. This sort of name-dropping might feel uncomfortable, but done gracefully, it can lend you credibility. Another tactic is to couple your assertions of competence with a degree of warmth. For example, you might say, “I’m excited to work with you because I’ve worked with similar clients over the past 10 years and we’ve gotten great results together,” or, “I’ve been in this field for 15 years because I love it and I’m looking forward to collaborating with you.” Statements like these allow you to put your expertise out there in a warm, friendly, cooperative way.