diff --git a/book/src/SUMMARY.md b/book/src/SUMMARY.md
index 54b4f3462..99ff6f90f 100644
--- a/book/src/SUMMARY.md
+++ b/book/src/SUMMARY.md
@@ -39,6 +39,7 @@
   - [Fork Selection](fork-selection.md)
   - [Reliable Vote Transmission](reliable-vote-transmission.md)
   - [Bank Forks](bank-forks.md)
+  - [Leader to Leader Transition](leader-leader-transition.md)
   - [Cluster Economics](ed_overview.md)
     - [Validation-client Economics](ed_validation_client_economics.md)
       - [State-validation Protocol-based Rewards](ed_vce_state_validation_protocol_based_rewards.md)
diff --git a/book/src/leader-leader-transition.md b/book/src/leader-leader-transition.md
new file mode 100644
index 000000000..84f1b2de7
--- /dev/null
+++ b/book/src/leader-leader-transition.md
@@ -0,0 +1,101 @@
+# Leader to Leader Transition
+
+This design describes how leaders transition production of the PoH ledger
+between each other as each leader generates its own slot.
+
+## Challenges
+
+Current leader and the next leader are both racing to generate the final tick
+for the current slot.  The next leader may arrive at that slot while still
+processing the current leader's entries.
+
+The ideal scenario would be that the next leader generated its own slot right
+after it was able to vote for the current leader.  It is very likely that the
+next leader will arrive at their PoH slot height before the current leader
+finishes broadcasting the entire block.
+
+The next leader has to make the decision of attaching its own block to the last
+completed block, or wait to finalize the pending block.  It is possible that the
+next leader will produce a block that proposes that the current leader failed,
+even though the rest of the network observes that block succeeding.
+
+The current leader has incentives to start its slot as early as possible to
+capture economic rewards.  Those incentives need to be balanced by the leader's
+need to attach its block to a block that has the most commitment from the rest
+of the network.
+
+## Leader timeout
+
+While a leader is actively receiving entries for the previous slot, the leader
+can delay broadcasting the start of its block in real time.  The delay is
+locally configurable by each leader, and can be dynamically based on the
+previous leader's behavior.  If the previous leader's block is confirmed by the
+leader's TVU before the timeout, the PoH is reset to the start of the slot and
+this leader produces its block immediately.
+
+The downsides:
+
+* Leader delays its own slot, potentially allowing the next leader more time to
+catch up.
+
+The upsides compared to guards:
+
+* All the space in a block is used for entries.
+
+* The timeout is not fixed.
+
+* The timeout is local to the leader, and therefore can be clever.  The leader's
+heuristic can take into account avalanche performance.
+
+* This design doesn't require a ledger hard fork to update.
+
+* The previous leader can redundantly transmit the last entry in the block to
+the next leader, and the next leader can speculatively decide to trust it to
+generate its block without verification of the previous block.
+
+* The leader can speculatively generate the last tick from the last received
+entry.
+
+* The leader can speculatively process transactions and guess which ones are not
+going to be encoded by the previous leader.  This is also a censorship attack
+vector.  The current leader may withhold transactions that it receives from the
+clients so it can encode them into its own slot. Once processed, entries can be
+replayed into PoH quickly.
+
+## Alternative design options
+
+### Guard tick at the end of the slot
+
+A leader does not produce entries in its block after the *penultimate tick*,
+which is the last tick before the first tick of the next slot.  The network
+votes on the *last tick*, so the time difference between the *penultimate tick*
+and the *last tick* is the forced delay for the entire network, as well as the
+next leader before a new slot can be generated.  The network can produce the
+*last tick* from the *penultimate tick*.
+
+If the next leader receives the *penultimate tick* before it produces its own
+*first tick*, it will reset its PoH and produce the *first tick* from the
+previous leader's *penultimate tick*.  The rest of the network will also reset
+its PoH to produce the *last tick* as the id to vote on.
+
+The downsides:
+
+* Every vote, and therefore confirmation, is delayed by a fixed timeout. 1 tick,
+or around 100ms.
+
+* Average case confirmation time for a transaction would be at least 50ms worse.
+
+* It is part of the ledger definition, so to change this behavior would require
+a hard fork.
+
+* Not all the available space is used for entries.
+
+The upsides compared to leader timeout:
+
+* The next leader has received all the previous entries, so it can start
+processing transactions without recording them into PoH.
+
+* The previous leader can redundantly transmit the last entry containing the
+*penultimate tick* to the next leader.  The next leader can speculatively
+generate the *last tick* as soon as it receives the *penultimate tick*, even
+before verifying it.