Dear Prof Hunt, Our company is about to have its Christmas party. The last two have been embarrassing. Our chief executive officer drinks too much and becomes more and more intimate with staff. I have worked for two other chief executives who organised excellent Christmas parties. What can you suggest to make this year a success?

What is the purpose of the Christmas party? To have fun and bond the staff? The anniversary of Christ's birth legitimises another special celebration - the closing of one chapter and the opening of another.

Such celebrations occur in all societies. Their function is to reinforce important beliefs. The same is true in a company. Although we cannot prove it, we sense that greater social cohesion should improve corporate performance.

So why do some Christmas parties fail? For two reasons. First, whereas religious celebrations have a purpose and time-tested rituals, corporate parties often lack both. Second, those in charge of the company do not realise that celebrations are about leadership.

Without leadership the celebration seems pointless. If we are to bond, we need a purpose. That is the CEO's function. If you want to avoid embarrassment this year, try to focus your CEO's attention on the following suggestions.

First, your boss must decide whom to invite: staff, spouses, clients? Most corporate parties are preceded by smaller gatherings of people who work closely together. In these cases, deciding who comes is easy. Such intimate celebrations require a confined space; privacy (so successes and failures can be discussed openly); flexibility (so no one gets trapped in the corner); a schedule (so we know what is planned) and a generous supply of refreshments.

In contrast, a company's official party may attract hundreds of employees and, in some cases, non-employees. These have just about everything working against them. There are too many people. There is an assumption that people from different levels of the company will mix and that they share common goals. In reality, most employees do not share the same day-to-day goals, nor do they mix up or down the hierarchy. My advice is to confine the party to employees only.

Second, the CEO's role as leader is vital. This should be one of the most important days of his year. In short, he has a captive and receptive audience.

No serious leader would miss this opportunity for a reaffirmation of commitment to the company. So your boss needs to understand he is on show. His prime function is to communicate the strategy for the company's new beginning.

Third, he must be sensitive to the situation or context. The greater the psychological distance between the leader and the led, the more formal the celebration will become. Part of your boss's job is to reduce that distance.

Behaviour that is acceptable in a close-knit team may be inappropriate in, for example, a gathering of call centre staff. Getting drunk with a group of sales executives may be acceptable to sales staff but unacceptable to everyone else.

Fourth, he should ensure the celebration has structure. The different backgrounds and interests of employees means they will not cohere, but will drift into natural subgroups. Only one fact binds them: they are employed by the same company. Of itself, this is not a basis for solidarity.

For this reason, your CEO's prime function is to give the Christmas party meaning. Unlike other get-togethers, the office Christmas party has a loose structure derived from past celebrations. Certain roles and routines are established in people's memories. These include the CEO's thank-you speech, the wearing of funny hats, awarding prizes for unlikely achievements plus the inevitable send-up of management. These recurring routines create roles for those who might normally have little influence within the company.

Your boss does not start from scratch. His role as a leader is already sanctioned. Consciously or not, we want to experience solidarity, if only for the day. All your boss must do is lead.

Fifth, the CEO must prepare a speech. It is the centrepiece of the drama. It should be brief and amusing but also all-encompassing and exciting. Even if the year has been a disaster, he needs to suggest that adversity will be overcome and the staff will be winners.

Sixth, having stimulated emotional solidarity by communicating direction, your CEO should circulate among the sub-groups as they re-form. Effective leaders communicate with groups and crowds to maximise their impact.

As he circulates, the CEO should confirm his plot, gather information, praise those who warrant it, assess reactions to his speech and show he is human. Conversely, this is not the time for intimate conversations with senior staff.

Finally, tell your CEO to leave the party before it ends. Staff must have time to talk about him. And as this is a social drama, he should dramatise his exit, perhaps by loudly wishing a merry Christmas and happy new year to all.