diff --git a/src/pkg/services/m365/api/item_serialization_test.go b/src/pkg/services/m365/api/item_serialization_test.go
new file mode 100644
index 000000000..a0f0f33b9
--- /dev/null
+++ b/src/pkg/services/m365/api/item_serialization_test.go
@@ -0,0 +1,135 @@
+package api_test
+
+import (
+	"context"
+	"fmt"
+	"testing"
+
+	"github.com/alcionai/clues"
+	"github.com/microsoftgraph/msgraph-sdk-go/models"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"github.com/stretchr/testify/suite"
+
+	"github.com/alcionai/corso/src/internal/common/ptr"
+	"github.com/alcionai/corso/src/internal/connector/support"
+	"github.com/alcionai/corso/src/internal/tester"
+	"github.com/alcionai/corso/src/pkg/services/m365/api"
+)
+
+type ItemSerializationUnitSuite struct {
+	tester.Suite
+}
+
+func TestItemSerializationUnitSuite(t *testing.T) {
+	suite.Run(t, &ItemSerializationUnitSuite{Suite: tester.NewUnitSuite(t)})
+}
+
+func (suite *ItemSerializationUnitSuite) TestConcurrentItemSerialization() {
+	var (
+		user      = "a-user"
+		instances = 100
+	)
+
+	table := []struct {
+		name                   string
+		serializer             func(t *testing.T, ctx context.Context, idx int) []byte
+		deserializeAndGetField func(t *testing.T, bs []byte) string
+	}{
+		{
+			name: "Exchange Mail",
+			serializer: func(t *testing.T, ctx context.Context, idx int) []byte {
+				subject := fmt.Sprintf("%d", idx)
+
+				item := models.NewMessage()
+				item.SetSubject(&subject)
+
+				bs, err := api.Mail{}.Serialize(ctx, item, user, subject)
+				require.NoError(t, err, clues.ToCore(err))
+
+				return bs
+			},
+			deserializeAndGetField: func(t *testing.T, bs []byte) string {
+				item, err := support.CreateMessageFromBytes(bs)
+				require.NoError(
+					t,
+					err,
+					"deserializing message of %q: %v",
+					string(bs),
+					clues.ToCore(err))
+
+				return ptr.Val(item.GetSubject())
+			},
+		},
+		{
+			name: "Exchange Event",
+			serializer: func(t *testing.T, ctx context.Context, idx int) []byte {
+				subject := fmt.Sprintf("%d", idx)
+
+				item := models.NewEvent()
+				item.SetSubject(&subject)
+
+				bs, err := api.Events{}.Serialize(ctx, item, user, subject)
+				require.NoError(t, err, clues.ToCore(err))
+
+				return bs
+			},
+			deserializeAndGetField: func(t *testing.T, bs []byte) string {
+				item, err := support.CreateEventFromBytes(bs)
+				require.NoError(
+					t,
+					err,
+					"deserializing event of %q: %v",
+					string(bs),
+					clues.ToCore(err))
+
+				return ptr.Val(item.GetSubject())
+			},
+		},
+		{
+			name: "Exchange Contact",
+			serializer: func(t *testing.T, ctx context.Context, idx int) []byte {
+				name := fmt.Sprintf("%d", idx)
+
+				item := models.NewContact()
+				item.SetGivenName(&name)
+
+				bs, err := api.Contacts{}.Serialize(ctx, item, user, name)
+				require.NoError(t, err, clues.ToCore(err))
+
+				return bs
+			},
+			deserializeAndGetField: func(t *testing.T, bs []byte) string {
+				item, err := support.CreateContactFromBytes(bs)
+				require.NoError(
+					t,
+					err,
+					"deserializing contact of %q: %v",
+					string(bs),
+					clues.ToCore(err))
+
+				return ptr.Val(item.GetGivenName())
+			},
+		},
+	}
+
+	for _, test := range table {
+		suite.Run(test.name, func() {
+			ctx, flusher := tester.NewContext()
+			defer flusher()
+
+			t := suite.T()
+			output := make([][]byte, instances)
+
+			for i := 0; i < instances; i++ {
+				output[i] = test.serializer(t, ctx, i)
+			}
+
+			for i := 0; i < instances; i++ {
+				got := test.deserializeAndGetField(t, output[i])
+				// I'm lazy and don't want to deal with the error from atoi functions.
+				assert.Equal(t, fmt.Sprintf("%d", i), got, "item output")
+			}
+		})
+	}
+}