diff --git a/client/src/error.rs b/client/src/error.rs
index 41a8688..b976c79 100644
--- a/client/src/error.rs
+++ b/client/src/error.rs
@@ -1,5 +1,8 @@
 #[derive(Debug, thiserror::Error, Clone)]
 pub enum Error {
+    #[error("Failed to authenticate with the given password")]
+    WrongPassword,
+
     #[error("Failed to handle a server response: {0}")]
     BadResponse(String),
 
@@ -14,4 +17,7 @@ pub enum Error {
 
     #[error("{0}")]
     Unknown(String),
+
+    #[error("The user was not found.")]
+    UserNotFound,
 }
diff --git a/client/src/lib.rs b/client/src/lib.rs
index 3711d10..a0d7160 100644
--- a/client/src/lib.rs
+++ b/client/src/lib.rs
@@ -6,6 +6,8 @@ pub use session::Session;
 #[cfg(test)]
 mod tests {
     use super::*;
+    use std::str::FromStr;
+    use uuid::Uuid;
 
     #[tokio::test]
     async fn authorized_session() {
@@ -15,7 +17,19 @@ mod tests {
             .expect("The environment variable ICRC_TEST_AUTH needs to be set!");
 
         let session = Session::new(&host, Some(token)).await.unwrap();
+    }
 
-        // assert_eq!(result, 4);
+    #[tokio::test]
+    async fn authenticate() {
+        let host = std::env::var("ICRC_TEST_HOST")
+            .expect("The environment variable ICRC_TEST_HOST needs to be set!");
+        let userid = std::env::var("ICRC_TEST_USER")
+            .expect("The environment variable ICRC_TEST_USER needs to be set!");
+
+        let mut session = Session::new(&host, None).await.unwrap();
+        session
+            .auth_with_credentials(Uuid::from_str(&userid).unwrap(), "test".to_string())
+            .await
+            .unwrap()
     }
 }
diff --git a/client/src/session/data.rs b/client/src/session/data.rs
index aaf45e2..ca7a3c8 100644
--- a/client/src/session/data.rs
+++ b/client/src/session/data.rs
@@ -12,6 +12,22 @@ pub mod api {
     pub mod account {
         use super::*;
 
+        pub mod auth {
+            use super::*;
+            use serde::Serialize;
+
+            #[derive(Debug, Serialize)]
+            pub struct Request {
+                pub userid: String,
+                pub password: String,
+            }
+
+            #[derive(Debug, Deserialize)]
+            pub struct Response {
+                pub token: String,
+            }
+        }
+
         pub mod info {
             use super::*;
 
diff --git a/client/src/session/mod.rs b/client/src/session/mod.rs
index ca4e73b..5adf1b0 100644
--- a/client/src/session/mod.rs
+++ b/client/src/session/mod.rs
@@ -1,12 +1,14 @@
 pub(self) mod data;
 
 use crate::error::Error;
+use reqwest::Response;
+use serde::de::DeserializeOwned;
 use std::str::FromStr;
 use uuid::Uuid;
 
 struct AuthorizedSession {
-    token: String,
-    userid: Uuid,
+    pub(self) token: String,
+    pub(self) userid: Uuid,
 }
 
 /// A Session is a connection to an ICRC Server.
@@ -15,10 +17,44 @@ struct AuthorizedSession {
 /// but an authorized session uses Bearer Authentication to get access to resources,
 /// which are not publicly accessible.
 pub struct Session {
-    host: String,
-    client: reqwest::Client,
+    pub(self) host: String,
+    pub(self) client: reqwest::Client,
 
-    auth: Option<AuthorizedSession>,
+    pub(self) auth: Option<AuthorizedSession>,
+}
+
+pub(self) async fn parse_response<T: DeserializeOwned>(
+    response: Result<Response, reqwest::Error>,
+) -> Result<T, Error> {
+    match response {
+        Ok(resp) => {
+            if resp.status().is_success() {
+                resp.json::<T>()
+                    .await
+                    .map_err(|e| Error::BadResponse(e.to_string()))
+            } else {
+                return Err(
+                    match resp
+                        .json::<data::api::error::Body>()
+                        .await
+                        .map_err(|e| Error::BadResponse(e.to_string()))?
+                        .error
+                    {
+                        data::api::error::Error::InvalidToken => Error::InvalidToken,
+                        data::api::error::Error::TokenExpired => Error::TokenExpired,
+                        e => Error::BadResponse(format!("Unknown Error/{e} in this context")),
+                    },
+                );
+            }
+        }
+        Err(e) => {
+            if e.is_connect() || e.is_timeout() {
+                Err(Error::ConnectionError)
+            } else {
+                Err(Error::Unknown(e.to_string()))
+            }
+        }
+    }
 }
 
 impl Session {
@@ -48,36 +84,10 @@ impl Session {
         let request = self
             .client
             .get(format!("{host}/account/info", host = self.host))
-            .bearer_auth(&token);
+            .bearer_auth(&token)
+            .send();
 
-        let response = match request.send().await {
-            Ok(resp) => {
-                if resp.status().is_success() {
-                    resp.json::<data::api::account::info::Response>()
-                        .await
-                        .map_err(|e| Error::BadResponse(e.to_string()))?
-                } else {
-                    return Err(
-                        match resp
-                            .json::<data::api::error::Body>()
-                            .await
-                            .map_err(|e| Error::BadResponse(e.to_string()))?
-                            .error
-                        {
-                            data::api::error::Error::InvalidToken => Error::InvalidToken,
-                            data::api::error::Error::TokenExpired => Error::TokenExpired,
-                            e => Error::BadResponse(format!("Unknown Error/{e} in this context")),
-                        },
-                    );
-                }
-            }
-            Err(e) => {
-                if e.is_connect() || e.is_timeout() {
-                    return Err(Error::ConnectionError);
-                }
-                return Err(Error::Unknown(e.to_string()));
-            }
-        };
+        let response = parse_response::<data::api::account::info::Response>(request.await).await?;
 
         self.auth = Some(AuthorizedSession {
             token,
@@ -87,4 +97,30 @@ impl Session {
 
         Ok(())
     }
+
+    /// Tries to authorize the session. If the credentials are not accepted by the server, this
+    /// leads to a [crate::error::Error::AuthenticationFailure] or [crate::error::Error::UserNotFound] error.
+    pub async fn auth_with_credentials(
+        &mut self,
+        userid: Uuid,
+        password: String,
+    ) -> Result<(), Error> {
+        let request = self
+            .client
+            .post(format!("{host}/account/auth", host = self.host))
+            .json(&data::api::account::auth::Request {
+                userid: userid.to_string(),
+                password,
+            })
+            .send();
+
+        let response = parse_response::<data::api::account::auth::Response>(request.await).await?;
+
+        self.auth = Some(AuthorizedSession {
+            token: response.token,
+            userid,
+        });
+
+        Ok(())
+    }
 }