Lady Windermere's Fan was Oscar Wilde's fourth play but his first dramatic success. His first three plays had been melodramatic tragedies, so the light social comedy was a major departure for him. The first act of the play establishes the setting, at the heart of fashionable London society, and introduces the four most important characters, Lord and Lady Windermere, Lord Darlington, and Mrs. Erlynne. Although only the first three of these characters actually appear on stage, Mrs. Erlynne is alluded to, and her position as a woman of mystery in an ambiguous situation is established.

Beyond this establishment of setting and characters which one might expect in act 1 of any play, the first act of Lady Windermere's Fan subtly misdirects the audience, laying the foundations of the dramatic surprise that is to occur later. The play's subtitle is A Play About a Good Woman. Lady Windermere's fastidious Puritanism in rebuking Lord Darlington in act 1 leads the audience to assume that she is the good woman in question. When she discovers that her husband has been making regular visits to Mrs. Erlynne and paying her large sums of money, the implication is that Lord Windermere and Mrs. Erlynne have been having an affair. Both these assumptions, which Wilde encourages, turn out to be wrong, allowing him to subvert the traditional morality play or "problem play" and lead his audience to question who the "good" characters really are.

The significance of the first scene of Oscar Wilde's first play Lady Windermere's Fan, is that it introduces the audience to the key players and key topics that will be treated through the play; second, by introducing these specific characters, it will offer the audience a sense of foreshadowing by stating, from the very beginning, the main problems surrounding Lady Windermere; third, Act I, as a whole, gives the audience a glimpse into the dynamics of a well-to-do London couple that is now being looked down upon as a result of what seems to be the indiscretion of a cheating husband. All of these small, sequential events prepare the audience to the myriad of puns, epigrams, and paradoxes that will come up in the dialogue all throughout the play, marking Wilde's unique and gracious style.

In this first scene, Lady Windermere, the young wife of a very respected Lord, is "of age" that day, and will have a great (highly fashionable, upper class) celebration that night. Her first visitor on this special day, Lord Darlington, is a seemingly-innocent family friend as well as a charming dandy. However, right there and then the audience finds out that Lord Darlington is in love with Lady Windermere and has been bold enough to make comments to the prudish woman in public in the past. This leads the audience to wonder: will this be the central problem of the story? Is there more to Lord Darlington's character than his attraction to Lady Windermere? Why has Lady Windermere, to this day, not ceased her acquaintance with a man who openly charms her? Is she as prudish as she seems?

The second significant instance in this scene is the entrance of the manipulative Duchess of Berwick; a woman of great social dominance who equally attempts to dominate every female around her. It is the Duchess of Berwick who brings the sad tidings to the Windermere household: Lord Windermere has been seen visiting and courting a woman, potentially supporting her financially, and even establishing her in a nearby apartment. 

He goes to see her continually..she has a great many disreputable men friends...and that is what makes it so dreadful about Windermere.

These news, combined with the introduction of the first two visitors, makes the audience wonder whether there will be a connection between Lord Darlington's intentions and the rumors surrounding Windermere. All of this will be developed during the Second Act.

Finally, and perhaps most importantly, Act I (as a whole) brings it all together; it shows the dynamics of the Windermeres as a socially-fashionable couple whose name is now stained by Lord Windermere's rumored indiscretion. In their dialogues, we notice that Lady Windermere is a woman far from feeble and "Victorian". We find, instead, a woman capable of deep anger and jealousy; she is even willing to publicly humiliate the other woman, whom her husband has had the gall to invite to her party. Moreover, Lord W. is also depicted as a man who does not appreciate his wife meddling in his private correspondence, and at one point obligates her to do as she is told.  Are they, then, not the perfect couple that they appear to be?

Therefore, much is said in this first scene, and in the first act, of the play. The opening scene, specifically places us at the "of age" birthday of Lady Windermere and shows the surprises that lie ahead for her during this very special day. These surprises will lead her to discover a part of her that she never thought she would find.

The main purpose of the opening act of Lady Windermere’s Fan by Oscar Wilde is to set the stage for the rest of the play. It establishes the wealth and social standing of the husband and wife, and places them within the context of fashionable British society. It also illustrates gender roles. Lady Windermere is established as a woman trying to sustain unfashionably strict ideas of virtue in an echelon of high society where that was regarded as a bit old fashioned.She states:

“There are moments when one has to choose between living one's own life, fully, entirely, completely-or dragging out some false, shallow, degrading existence that the world in its hypocrisy demands.”

The main conflict of the play, Lady Windermere concern that her husband is having an affair with Mrs Erlynne, and the opinions of fashionable society about adultery are also established in the first act.