diff --git a/src/app.py b/src/app.py
index 4ebb1d9..27ea0e6 100644
--- a/src/app.py
+++ b/src/app.py
@@ -38,6 +38,45 @@
         "schedule": "Mondays, Wednesdays, Fridays, 2:00 PM - 3:00 PM",
         "max_participants": 30,
         "participants": ["john@mergington.edu", "olivia@mergington.edu"]
+    },
+    # Sports related activities
+    "Soccer Team": {
+        "description": "Join the school soccer team and compete in matches",
+        "schedule": "Wednesdays, 4:00 PM - 5:30 PM",
+        "max_participants": 18,
+        "participants": ["alex@mergington.edu", "lucas@mergington.edu"]
+    },
+    "Basketball Club": {
+        "description": "Practice basketball skills and play friendly games",
+        "schedule": "Thursdays, 3:30 PM - 5:00 PM",
+        "max_participants": 15,
+        "participants": ["mia@mergington.edu", "noah@mergington.edu"]
+    },
+    # Artistic activities
+    "Art Workshop": {
+        "description": "Explore painting, drawing, and sculpture techniques",
+        "schedule": "Mondays, 4:00 PM - 5:30 PM",
+        "max_participants": 16,
+        "participants": ["ava@mergington.edu", "liam@mergington.edu"]
+    },
+    "Drama Club": {
+        "description": "Act, direct, and produce school plays and performances",
+        "schedule": "Tuesdays, 3:30 PM - 5:00 PM",
+        "max_participants": 20,
+        "participants": ["ella@mergington.edu", "jack@mergington.edu"]
+    },
+    # Intellectual activities
+    "Mathletes": {
+        "description": "Compete in math competitions and solve challenging problems",
+        "schedule": "Fridays, 4:00 PM - 5:00 PM",
+        "max_participants": 10,
+        "participants": ["oliver@mergington.edu", "isabella@mergington.edu"]
+    },
+    "Science Club": {
+        "description": "Conduct experiments and explore scientific concepts",
+        "schedule": "Wednesdays, 3:30 PM - 4:30 PM",
+        "max_participants": 14,
+        "participants": ["charlotte@mergington.edu", "benjamin@mergington.edu"]
     }
 }
 
@@ -62,6 +101,10 @@ def signup_for_activity(activity_name: str, email: str):
     # Get the specific activity
     activity = activities[activity_name]
 
+    # Check if already signed up
+    if email in activity["participants"]:
+        raise HTTPException(status_code=400, detail="Already signed up for this activity")  
+    
     # Add student
     activity["participants"].append(email)
     return {"message": f"Signed up {email} for {activity_name}"}
diff --git a/src/static/app.js b/src/static/app.js
index dcc1e38..548ac31 100644
--- a/src/static/app.js
+++ b/src/static/app.js
@@ -25,6 +25,14 @@ document.addEventListener("DOMContentLoaded", () => {
           <p>${details.description}</p>
           <p><strong>Schedule:</strong> ${details.schedule}</p>
           <p><strong>Availability:</strong> ${spotsLeft} spots left</p>
+          <div class="activity-card-participants">
+            <h5>Participants</h5>
+            <ul>
+              ${details.participants.length === 0
+                ? '<li><em>Aucun participant pour le moment</em></li>'
+                : details.participants.map(p => `<li>${p}</li>`).join('')}
+            </ul>
+          </div>
         `;
 
         activitiesList.appendChild(activityCard);
diff --git a/src/static/styles.css b/src/static/styles.css
index a533b32..30923ad 100644
--- a/src/static/styles.css
+++ b/src/static/styles.css
@@ -74,6 +74,44 @@ section h3 {
   margin-bottom: 8px;
 }
 
+.activity-card-participants {
+  margin-top: 15px;
+  padding: 12px 15px;
+  border-radius: 4px;
+  background-color: white;
+  border-top: 1px solid #e3e7ef;
+  box-shadow: 0 1px 2px rgba(26, 35, 126, 0.04);
+}
+
+.activity-card-participants h5 {
+  margin-bottom: 10px;
+  color: #1a237e;
+  font-size: 1.05rem;
+  font-weight: bold;
+  letter-spacing: 0.5px;
+}
+
+.activity-card-participants ul {
+  list-style-type: disc;
+  padding-left: 22px;
+  margin-bottom: 0;
+}
+
+.activity-card-participants li {
+  margin-bottom: 6px;
+  color: #3949ab;
+  font-size: 0.98rem;
+  font-weight: 500;
+  background: transparent;
+  border-radius: 2px;
+  transition: background 0.2s;
+}
+
+.activity-card-participants li:hover {
+  background: #e3eafc;
+  padding-left: 2px;
+}
+
 .form-group {
   margin-bottom: 15px;
 }