@@ -13,7 +13,7 @@ Looking to upgrade from Sentry SDK 2.x to 3.x? Here's a comprehensive list of wh
 - If a `before_breadcrumb` callback, an event processor, or an error processor raises an exception, the breadcrumb or event is now dropped. Previously, the SDK would log the exception and continue processing the unmodified breadcrumb or event.
 - The top-level manual tracing API is now wired to span streaming tracing:
   - `sentry_sdk.start_transaction` doesn't exist anymore. Use `sentry_sdk.start_span` instead.
-  - `sentry_sdk.start_span` accepts four arguments now: `name` (mandatory), `attributes`, `parent_span` (default: current active span), `active` (default: `True`).
+  - `sentry_sdk.start_span` accepts five arguments now: `name` (mandatory), `attributes`, `parent_span` (default: current active span), `active` (default: `True`), `links` (spans to link to without making them the parent; more can be added with `span.add_link()` / `span.add_links()`).
   - The `@trace` decorator accepts three optional arguments: `name`, `attributes`, `active` (default: `True`).
   - `sentry_sdk.continue_trace` accepts a single dictionary with the incoming headers or environment data. It is no longer a context manager and it does not return a span/transaction anymore. A span needs to be started manually afterwards.
   - `sentry_sdk.new_trace` resets the trace.
 
@@ -159,7 +159,12 @@ def _estimate_size(item: "SpanJSON") -> int:
         # 210 is the rough size of the payload without attributes, and then we
         # estimate the attributes separately.
         estimate = 210
-        for value in (item.get("attributes") or {}).values():
+        attribute_values = list((item.get("attributes") or {}).values())
+        for link in item.get("links") or ():
+            estimate += 100
+            attribute_values.extend((link.get("attributes") or {}).values())
+
+        for value in attribute_values:
             estimate += 50
 
             if isinstance(value, str):
@@ -180,6 +185,22 @@ def _to_transport_format(item: "SpanJSON") -> "Any":
         else:
             del res["attributes"]
 
+        if item.get("links"):
+            res["links"] = []
+            for link in item["links"]:
+                if "attributes" in link:
+                    res["links"].append(  # type: ignore[attr-defined]
+                        {
+                            **link,
+                            "attributes": {
+                                k: serialize_attribute(v)
+                                for (k, v) in link["attributes"].items()
+                            },
+                        }
+                    )
+                else:
+                    res["links"].append(link)  # type: ignore[attr-defined]
+
         return res
 
     def _flush(self, only_pending: bool = False) -> None:
 
@@ -364,6 +364,16 @@ class DataCollection(TypedDict):
 
     MetricProcessor = Callable[[Metric, Hint], Optional[Metric]]
 
+    SpanLink = TypedDict(
+        "SpanLink",
+        {
+            "span_id": str,
+            "trace_id": str,
+            "sampled": NotRequired[bool],
+            "attributes": NotRequired[Attributes],
+        },
+    )
+
     SpanJSON = TypedDict(
         "SpanJSON",
         {
@@ -376,6 +386,7 @@ class DataCollection(TypedDict):
             "start_timestamp": float,
             "end_timestamp": NotRequired[float],
             "attributes": NotRequired[Attributes],
+            "links": NotRequired[list[SpanLink]],
             "_segment_span": NotRequired["sentry_sdk.traces.Span"],
         },
     )
 
@@ -76,6 +76,7 @@
         Log,
         LogLevelStr,
         Metric,
+        SpanLink,
         Type,
     )
 
@@ -937,6 +938,7 @@ def start_span(
         attributes: "Optional[Attributes]",
         parent_span: "Optional[Span]",
         active: bool,
+        links: "Optional[list[SpanLink]]" = None,
     ) -> "Span":
         """
         Start a span.
@@ -987,6 +989,11 @@ def start_span(
             provided explicitly via the `parent_span` argument), set this to `False`.
         :type active: bool
 
+        :param links: Spans to link the span to, without making them its parent,
+            e.g. in other traces. More can be added with `span.add_link()` or
+            `span.add_links()`.
+        :type links: "Optional[list[SpanLink]]"
+
         :return: The span that has been started.
         :rtype: Span
         """
@@ -1055,6 +1062,7 @@ def start_span(
                 baggage=propagation_context.baggage,
                 sample_rand=sample_rand,
                 sample_rate=sample_rate,
+                links=links,
             )
 
         # This is a child span; take propagation context from the parent span
@@ -1090,6 +1098,7 @@ def start_span(
                 trace_id=parent_span.trace_id,
                 parent_span_id=parent_span.span_id,
                 parent_sampled=parent_span.sampled,
+                links=links,
             )
 
     def _update_sample_rate(self, sample_rate: float) -> None:
 
@@ -1,3 +1,4 @@
+import copy
 import sys
 import uuid
 from datetime import datetime, timedelta, timezone
@@ -33,7 +34,7 @@
         overload,
     )
 
-    from sentry_sdk._types import Attributes, AttributeValue, SpanJSON
+    from sentry_sdk._types import Attributes, AttributeValue, SpanJSON, SpanLink
     from sentry_sdk.profiler.continuous_profiler import ContinuousProfile
 
     P = ParamSpec("P")
@@ -132,10 +133,11 @@ def start_span(
     attributes: "Optional[Attributes]" = None,
     parent_span: "Optional[Span]" = _DEFAULT_PARENT_SPAN,  # type: ignore[assignment]
     active: bool = True,
+    links: "Optional[list[SpanLink]]" = None,
 ) -> "Span":
 
     return sentry_sdk.get_current_scope().start_span(
-        name, attributes, parent_span, active
+        name, attributes, parent_span, active, links
     )
 
 
@@ -171,6 +173,7 @@ class Span:
     __slots__ = (
         "_name",
         "_attributes",
+        "_links",
         "_active",
         "_span_id",
         "_trace_id",
@@ -203,6 +206,7 @@ def __init__(
         baggage: "Optional[Baggage]" = None,
         sample_rate: "Optional[float]" = None,
         sample_rand: "Optional[float]" = None,
+        links: "Optional[list[SpanLink]]" = None,
     ):
         self._name: str = name
         self._active: bool = active
@@ -215,6 +219,10 @@ def __init__(
             for attribute, value in attributes.items():
                 self.set_attribute(attribute, value)
 
+        self._links: "list[SpanLink]" = []
+        if links:
+            self.add_links(links)
+
         self._scope = scope
 
         self._segment = segment or self
@@ -372,6 +380,21 @@ def remove_attribute(self, key: str) -> None:
         except KeyError:
             pass
 
+    def add_link(self, link: "SpanLink") -> None:
+        stored: "SpanLink" = {"trace_id": link["trace_id"], "span_id": link["span_id"]}
+        if "sampled" in link:
+            stored["sampled"] = link["sampled"]
+        if link.get("attributes"):
+            stored["attributes"] = {
+                key: format_attribute(value)
+                for key, value in link["attributes"].items()
+            }
+        self._links.append(stored)
+
+    def add_links(self, links: "list[SpanLink]") -> None:
+        for link in links:
+            self.add_link(link)
+
     @property
     def status(self) -> "str":
         return self._status
@@ -551,6 +574,9 @@ def _to_json(self) -> "SpanJSON":
 
         res["attributes"] = {k: v for k, v in self._attributes.items()}
 
+        if self._links:
+            res["links"] = copy.deepcopy(self._links)
+
         return res
 
 
@@ -674,6 +700,12 @@ def set_attributes(self, attributes: "Attributes") -> None:
     def remove_attribute(self, key: str) -> None:
         pass
 
+    def add_link(self, link: "SpanLink") -> None:
+        pass
+
+    def add_links(self, links: "list[SpanLink]") -> None:
+        pass
+
     @property
     def status(self) -> "str":
         return SpanStatus.OK.value
 
@@ -284,6 +284,7 @@ def test_before_send_span_unsupported_edit(sentry_init, capture_items):
     def before_send_span(span, hint):
         # Anything beyond attribute and name changes will be ignored
         span["trace_id"] = "my-trace-id"
+        span["links"][0]["attributes"]["kind"] = "changed"
 
         return span
 
@@ -294,7 +295,8 @@ def before_send_span(span, hint):
 
     items = capture_items("span")
 
-    with sentry_sdk.start_span(name="span"):
+    link = {"trace_id": "a" * 32, "span_id": "b" * 16, "attributes": {"kind": "a"}}
+    with sentry_sdk.start_span(name="span", links=[link]):
         ...
 
     sentry_sdk.flush()
@@ -305,6 +307,7 @@ def before_send_span(span, hint):
 
     assert span["name"] == "span"
     assert span["trace_id"] != "my-trace-id"
+    assert span["links"][0]["attributes"]["kind"] == {"type": "string", "value": "a"}
 
 
 def test_before_send_span_doesnt_receive_ignored_spans(sentry_init, capture_items):
@@ -435,6 +438,80 @@ class Class:
     assert "Class" in span["attributes"]["attribute2"]
 
 
+def test_span_links(sentry_init, capture_envelopes):
+    sentry_init(
+        traces_sample_rate=1.0,
+    )
+
+    envelopes = capture_envelopes()
+
+    previous_trace = {
+        "trace_id": "627a2885119dcc8184fae7eef09438cb",
+        "span_id": "6c71fc6b09b8b716",
+        "sampled": True,
+        "attributes": {"sentry.link.type": "previous_trace"},
+    }
+    with sentry_sdk.start_span(name="parent", links=[previous_trace]) as span:
+        span.add_link({"trace_id": "a" * 32, "span_id": "b" * 16})
+        span.add_links(
+            [
+                {
+                    "trace_id": "c" * 32,
+                    "span_id": "d" * 16,
+                    "sampled": False,
+                    "attributes": {"messaging.message.id": "1", "retries": 2},
+                }
+            ]
+        )
+        with sentry_sdk.start_span(name="child"):
+            ...
+        # span keeps its own copy.
+        previous_trace["attributes"]["sentry.link.type"] = "changed"
+
+    sentry_sdk.flush()
+    child, span = envelopes[0].items[0].payload.json["items"]
+
+    # empty `links` array is omitted.
+    assert "links" not in child
+    assert span["links"] == [
+        {
+            "trace_id": "627a2885119dcc8184fae7eef09438cb",
+            "span_id": "6c71fc6b09b8b716",
+            "sampled": True,
+            "attributes": {
+                "sentry.link.type": {"type": "string", "value": "previous_trace"}
+            },
+        },
+        {"trace_id": "a" * 32, "span_id": "b" * 16},
+        {
+            "trace_id": "c" * 32,
+            "span_id": "d" * 16,
+            "sampled": False,
+            "attributes": {
+                "messaging.message.id": {"type": "string", "value": "1"},
+                "retries": {"type": "integer", "value": 2},
+            },
+        },
+    ]
+
+
+def test_span_links_on_noop_span(sentry_init, capture_items):
+    sentry_init(
+        traces_sample_rate=0.0,
+    )
+
+    items = capture_items("span")
+
+    link = {"trace_id": "a" * 32, "span_id": "b" * 16}
+    with sentry_sdk.start_span(name="parent", links=[link]) as span:
+        assert isinstance(span, NoOpSpan)
+        span.add_link(link)
+        span.add_links([link])
+
+    sentry_sdk.flush()
+    assert items == []
+
+
 def test_traces_sampler_drops_span(sentry_init, capture_items):
     def traces_sampler(sampling_context):
         assert "data" in sampling_context["transaction_context"]