diff --git a/Cargo.lock b/Cargo.lock
index c368d0712..1616d24bb 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -4824,6 +4824,7 @@ dependencies = [
  "sparrow-runtime",
  "sparrow-syntax",
  "static_init",
+ "tempfile",
  "tokio",
  "tokio-stream",
  "uuid 1.4.1",
diff --git a/crates/sparrow-runtime/src/prepare/preparer.rs b/crates/sparrow-runtime/src/prepare/preparer.rs
index 41408a7dc..bbf1f3ea3 100644
--- a/crates/sparrow-runtime/src/prepare/preparer.rs
+++ b/crates/sparrow-runtime/src/prepare/preparer.rs
@@ -93,13 +93,16 @@ impl Preparer {
     /// - This adds or casts columns as needed.
     /// - This produces multiple parts if the input file is large.
     /// - This produces metadata files alongside data files.
+    /// Parameters:
+    /// - `to_prepare`: The path to the parquet file to prepare.
+    /// - `prepared_dir`: The directory to write the prepared files to.
     pub async fn prepare_parquet(
         &self,
-        path: &std::path::Path,
+        to_prepare: &std::path::Path,
+        prepared_dir: &std::path::Path,
     ) -> error_stack::Result<Vec<PreparedFile>, Error> {
         // TODO: Support Slicing
-
-        let output_path_prefix = self.prepared_output_prefix();
+        let output_path_prefix = self.prepared_output_prefix(prepared_dir);
         let output_url = ObjectStoreUrl::from_str(&output_path_prefix)
             .change_context_lazy(|| Error::InvalidUrl(output_path_prefix))?;
 
@@ -110,7 +113,7 @@ impl Preparer {
 
         let source_data = SourceData {
             source: Some(
-                SourceData::try_from_local(path)
+                SourceData::try_from_local(to_prepare)
                     .into_report()
                     .change_context(Error::Internal)?,
             ),
@@ -180,17 +183,21 @@ impl Preparer {
             self.time_multiplier.as_ref(),
         )
     }
-    // Prepared files are stored in the following format:
-    // file:///<temp_dir>/<KASKADA_PATH>/tables/<table_uuid>/prepared/<uuid>/part-<n>.parquet
-    pub fn prepared_output_prefix(&self) -> String {
+
+    /// Creates the local output prefix to use for prepared files.
+    ///
+    /// e.g. for osx: file:///<dir>/<KASKADA_PATH>/tables/<table_uuid>/prepared/<uuid>
+    pub fn prepared_output_prefix(&self, dir: &std::path::Path) -> String {
         let uuid = Uuid::new_v4();
-        let temp_dir = tempfile::tempdir().expect("failed to create temp dir");
-        format!(
-            "file:///{}/{}/tables/{}/prepare/{uuid}/",
-            temp_dir.path().display(),
-            KASKADA_PATH,
-            self.table_config.uuid
-        )
+
+        // Construct the path using PathBuf to handle platform-specific path separators.
+        let mut buf = std::path::PathBuf::new();
+        buf.push(dir);
+        buf.push(KASKADA_PATH);
+        buf.push("tables");
+        buf.push("prepare");
+        buf.push(uuid.to_string());
+        buf.to_string_lossy().to_string()
     }
 }
 
diff --git a/crates/sparrow-session/Cargo.toml b/crates/sparrow-session/Cargo.toml
index 117bcab16..67d125d4a 100644
--- a/crates/sparrow-session/Cargo.toml
+++ b/crates/sparrow-session/Cargo.toml
@@ -26,6 +26,7 @@ sparrow-runtime = { path = "../sparrow-runtime" }
 sparrow-syntax = { path = "../sparrow-syntax" }
 sparrow-instructions = { path = "../sparrow-instructions" }
 static_init.workspace = true
+tempfile.workspace = true
 tokio.workspace = true
 tokio-stream.workspace = true
 uuid.workspace = true
diff --git a/crates/sparrow-session/src/session.rs b/crates/sparrow-session/src/session.rs
index 5e9d8cbdc..d592a402b 100644
--- a/crates/sparrow-session/src/session.rs
+++ b/crates/sparrow-session/src/session.rs
@@ -34,10 +34,16 @@ pub struct Session {
     udfs: HashMap<Uuid, Arc<dyn Udf>>,
     object_store_registry: Arc<ObjectStoreRegistry>,
     rt: tokio::runtime::Runtime,
+    /// Temporary directory to hold prepared files for this session.
+    ///
+    /// Creating in the session ensures it won't be dropped until the
+    /// session is closed.
+    prepared_dir: tempfile::TempDir,
 }
 
 impl Default for Session {
     fn default() -> Self {
+        let prepared_dir = tempfile::tempdir().expect("failed to create temp dir");
         Self {
             data_context: Default::default(),
             dfg: Default::default(),
@@ -45,6 +51,7 @@ impl Default for Session {
             udfs: Default::default(),
             object_store_registry: Default::default(),
             rt: tokio::runtime::Runtime::new().expect("tokio runtime"),
+            prepared_dir,
         }
     }
 }
@@ -125,7 +132,7 @@ impl Session {
         grouping_name: Option<&str>,
         time_unit: Option<&str>,
         source: Option<&str>,
-    ) -> error_stack::Result<Table, Error> {
+    ) -> error_stack::Result<Table<'_>, Error> {
         let uuid = Uuid::new_v4();
         let schema_proto = sparrow_api::kaskada::v1alpha::Schema::try_from(schema.as_ref())
             .into_report()
@@ -188,6 +195,7 @@ impl Session {
             time_unit,
             self.object_store_registry.clone(),
             source,
+            self.prepared_dir.path(),
         )
     }
 
diff --git a/crates/sparrow-session/src/table.rs b/crates/sparrow-session/src/table.rs
index debbdc627..0dcc5674f 100644
--- a/crates/sparrow-session/src/table.rs
+++ b/crates/sparrow-session/src/table.rs
@@ -17,13 +17,14 @@ use sparrow_runtime::{key_hash_inverse::ThreadSafeKeyHashInverse, stores::Object
 
 use crate::{Error, Expr};
 
-pub struct Table {
+pub struct Table<'a> {
     pub expr: Expr,
     preparer: Preparer,
     key_column: usize,
     key_hash_inverse: Arc<ThreadSafeKeyHashInverse>,
     source: Source,
     registry: Arc<ObjectStoreRegistry>,
+    prepared_dir: &'a std::path::Path,
 }
 
 #[derive(Debug)]
@@ -32,7 +33,7 @@ enum Source {
     Parquet(Arc<FileSets>),
 }
 
-impl Table {
+impl<'a> Table<'a> {
     #[allow(clippy::too_many_arguments)]
     pub(crate) fn new(
         table_info: &mut TableInfo,
@@ -43,6 +44,7 @@ impl Table {
         time_unit: Option<&str>,
         object_stores: Arc<ObjectStoreRegistry>,
         source: Option<&str>,
+        prepared_dir: &'a std::path::Path,
     ) -> error_stack::Result<Self, Error> {
         let prepared_fields: Fields = KEY_FIELDS
             .iter()
@@ -99,6 +101,7 @@ impl Table {
             key_column: key_column + KEY_FIELDS.len(),
             source,
             registry: object_stores,
+            prepared_dir,
         })
     }
 
@@ -145,7 +148,7 @@ impl Table {
 
         let prepared = self
             .preparer
-            .prepare_parquet(path)
+            .prepare_parquet(path, self.prepared_dir)
             .await
             .change_context(Error::Prepare)?;