diff --git a/beacon_chain.nimble b/beacon_chain.nimble
index 8c0f32a08..78ce5125d 100644
--- a/beacon_chain.nimble
+++ b/beacon_chain.nimble
@@ -57,11 +57,8 @@ task test, "Run all tests":
   #buildBinary "test_fixture_ssz_static", "tests/official/", "-r -d:release -d:chronicles_log_level=DEBUG -d:const_preset=minimal"
   #buildBinary "test_fixture_ssz_static", "tests/official/", "-r -d:release -d:chronicles_log_level=DEBUG -d:const_preset=mainnet"
 
-  buildBinary "transition_0_9_0", "tests/", "-r -d:release -d:chronicles_log_level=DEBUG -d:const_preset=minimal"
-  buildBinary "transition_0_9_0", "tests/", "-r -d:release -d:chronicles_log_level=DEBUG -d:const_preset=mainnet"
-
-  #buildBinary "all_fixtures_require_ssz", "tests/official/", "-r -d:release -d:chronicles_log_level=DEBUG -d:const_preset=minimal"
-  #buildBinary "all_fixtures_require_ssz", "tests/official/", "-r -d:release -d:chronicles_log_level=DEBUG -d:const_preset=mainnet"
+  buildBinary "all_fixtures_require_ssz", "tests/official/", "-r -d:release -d:chronicles_log_level=DEBUG -d:const_preset=minimal"
+  buildBinary "all_fixtures_require_ssz", "tests/official/", "-r -d:release -d:chronicles_log_level=DEBUG -d:const_preset=mainnet"
 
   # State sim; getting into 3rd epoch useful
   buildBinary "state_sim", "research/", "-r -d:release", "--validators=128 --slots=24"
diff --git a/beacon_chain/beacon_node.nim b/beacon_chain/beacon_node.nim
index a75670f0f..aef73320c 100644
--- a/beacon_chain/beacon_node.nim
+++ b/beacon_chain/beacon_node.nim
@@ -513,7 +513,8 @@ proc handleAttestations(node: BeaconNode, head: BlockRef, slot: Slot) =
     var cache = get_empty_per_epoch_cache()
     let
       epoch = compute_epoch_at_slot(slot)
-      committees_per_slot = get_committee_count(state, epoch) div SLOTS_PER_EPOCH
+      committees_per_slot =
+        get_committee_count_at_slot(state, epoch.compute_start_slot_at_epoch)
       offset = committees_per_slot * (slot mod SLOTS_PER_EPOCH)
       slot_start_shard = (get_start_shard(state, epoch) + offset) mod SHARD_COUNT
 
diff --git a/beacon_chain/spec/beaconstate.nim b/beacon_chain/spec/beaconstate.nim
index 3053ad8ae..c6d546690 100644
--- a/beacon_chain/spec/beaconstate.nim
+++ b/beacon_chain/spec/beaconstate.nim
@@ -303,7 +303,8 @@ func get_attestation_data_slot*(state: BeaconState,
 func get_attestation_data_slot*(state: BeaconState,
     data: AttestationData): Slot =
   get_attestation_data_slot(
-    state, data, get_committee_count(state, data.target.epoch))
+    state, data, get_committee_count_at_slot(
+      state, data.target.epoch.compute_start_slot_at_epoch) * SLOTS_PER_EPOCH)
 
 # https://github.com/ethereum/eth2.0-specs/blob/v0.9.0/specs/core/0_beacon-chain.md#get_block_root_at_slot
 func get_block_root_at_slot*(state: BeaconState,
diff --git a/beacon_chain/spec/datatypes.nim b/beacon_chain/spec/datatypes.nim
index 9777b5f48..06a40049f 100644
--- a/beacon_chain/spec/datatypes.nim
+++ b/beacon_chain/spec/datatypes.nim
@@ -665,11 +665,6 @@ chronicles.formatIt Epoch: it.shortLog
 chronicles.formatIt BeaconBlock: it.shortLog
 chronicles.formatIt AttestationData: it.shortLog
 
-static:
-  # Ensure that get_crosslink_committee(...) can access all committees, which
-  # requires that SHARD_COUNT >= get_committee_count(...)
-  doAssert SHARD_COUNT >= SLOTS_PER_EPOCH, "Shard count should match or exceed number of slots per epoch"
-
 import json_serialization
 export json_serialization
 export writeValue, readValue
diff --git a/beacon_chain/spec/helpers.nim b/beacon_chain/spec/helpers.nim
index 75c648e54..75831372f 100644
--- a/beacon_chain/spec/helpers.nim
+++ b/beacon_chain/spec/helpers.nim
@@ -54,7 +54,7 @@ func get_active_validator_indices*(state: BeaconState, epoch: Epoch):
     if is_active_validator(val, epoch):
       result.add idx.ValidatorIndex
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.9.0/specs/core/0_beacon-chain.md#get_committee_count
+# https://github.com/ethereum/eth2.0-specs/blob/v0.9.0/specs/core/0_beacon-chain.md#get_committee_count_at_slot
 func get_committee_count_at_slot*(state: BeaconState, slot: Slot): uint64 =
   # Return the number of committees at ``slot``.
   let epoch = compute_epoch_at_slot(slot)
@@ -68,18 +68,6 @@ func get_committee_count_at_slot*(state: BeaconState, slot: Slot): uint64 =
   # committees.
   doAssert (SLOTS_PER_EPOCH * MAX_COMMITTEES_PER_SLOT).uint64 >= result
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#get_committee_count
-func get_committee_count*(state: BeaconState, epoch: Epoch): uint64 =
-  # Return the number of committees at ``epoch``.
-  let active_validator_indices = get_active_validator_indices(state, epoch)
-  let committees_per_slot = clamp(
-    len(active_validator_indices) div SLOTS_PER_EPOCH div TARGET_COMMITTEE_SIZE,
-    1, SHARD_COUNT div SLOTS_PER_EPOCH).uint64
-  result = committees_per_slot * SLOTS_PER_EPOCH
-
-  # Otherwise, get_crosslink_committee(...) cannot access some committees.
-  doAssert SHARD_COUNT >= result
-
 # https://github.com/ethereum/eth2.0-specs/blob/v0.9.0/specs/core/0_beacon-chain.md#get_current_epoch
 func get_current_epoch*(state: BeaconState): Epoch =
   # Return the current epoch.
diff --git a/beacon_chain/spec/presets/mainnet.nim b/beacon_chain/spec/presets/mainnet.nim
index 141b07717..32fbba5eb 100644
--- a/beacon_chain/spec/presets/mainnet.nim
+++ b/beacon_chain/spec/presets/mainnet.nim
@@ -24,10 +24,9 @@ const
 
   MAX_COMMITTEES_PER_SLOT* = 64
 
-  SHARD_COUNT* {.intdefine.} = 1024 ##\
-  ## Number of shards supported by the network - validators will jump around
-  ## between these shards and provide attestations to their state.
-  ## Compile with -d:SHARD_COUNT=4 for fewer shard (= better with low validator counts)
+  # TODO remove
+  SHARD_COUNT* = 2048 ##\
+  ## SLOTS_PER_EPOCH * MAX_COMMITTEES_PER_SLOT
 
   TARGET_COMMITTEE_SIZE* = 2^7 ##\
   ## Number of validators in the committee attesting to one shard
diff --git a/beacon_chain/spec/presets/minimal.nim b/beacon_chain/spec/presets/minimal.nim
index da6f9bf1c..be0e2d993 100644
--- a/beacon_chain/spec/presets/minimal.nim
+++ b/beacon_chain/spec/presets/minimal.nim
@@ -22,13 +22,14 @@ const
   # ---------------------------------------------------------------
   # https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/configs/minimal.yaml#L4
 
-  # TODO remove
-  SHARD_COUNT* {.intdefine.} = 8
-
   # Changed
   MAX_COMMITTEES_PER_SLOT* = 4
   TARGET_COMMITTEE_SIZE* = 4
 
+  # TODO remove
+  SHARD_COUNT* = 32 ##\
+  ## SLOTS_PER_EPOCH * MAX_COMMITTEES_PER_SLOT
+
   # Unchanged
   MAX_VALIDATORS_PER_COMMITTEE* = 2048
   MIN_PER_EPOCH_CHURN_LIMIT* = 4
diff --git a/beacon_chain/spec/state_transition_helpers.nim b/beacon_chain/spec/state_transition_helpers.nim
index bc7e8dd7e..6fdf8f9b5 100644
--- a/beacon_chain/spec/state_transition_helpers.nim
+++ b/beacon_chain/spec/state_transition_helpers.nim
@@ -24,7 +24,7 @@ func shortLog*(x: Checkpoint): string =
 
 # https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#get_attesting_indices
 # TODO there's another one of these, check for redundancy
-func get_attesting_indices*(
+func get_attesting_indices(
     state: BeaconState, attestations: openarray[PendingAttestation],
     stateCache: var StateCache): HashSet[ValidatorIndex] =
   result = initSet[ValidatorIndex]()
diff --git a/beacon_chain/spec/validator.nim b/beacon_chain/spec/validator.nim
index 14e645e3a..9911acc9d 100644
--- a/beacon_chain/spec/validator.nim
+++ b/beacon_chain/spec/validator.nim
@@ -91,7 +91,8 @@ func get_previous_epoch*(state: BeaconState): Epoch =
 func get_shard_delta*(state: BeaconState, epoch: Epoch): uint64 =
   ## Return the number of shards to increment ``state.start_shard``
   ## during ``epoch``.
-  min(get_committee_count(state, epoch),
+  min(get_committee_count_at_slot(state, epoch.compute_start_slot_at_epoch) *
+      SLOTS_PER_EPOCH,
     (SHARD_COUNT - SHARD_COUNT div SLOTS_PER_EPOCH).uint64)
 
 # https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#get_start_shard
@@ -159,11 +160,12 @@ func compute_committee(indices: seq[ValidatorIndex], seed: Eth2Digest,
     start.int .. (endIdx.int-1),
     indices[stateCache.crosslink_committee_cache[key][it]])
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#get_beacon_committee
+# https://github.com/ethereum/eth2.0-specs/blob/v0.9.0/specs/core/0_beacon-chain.md#get_beacon_committee
 func get_beacon_committee*(state: BeaconState, slot: Slot, index: uint64, cache: var StateCache): seq[ValidatorIndex] =
   # Return the beacon committee at ``slot`` for ``index``.
   let
     epoch = compute_epoch_at_slot(slot)
+    # TODO use state caching for this or not?
     committees_per_slot = get_committee_count_at_slot(state, slot)
 
   ## This is a somewhat more fragile, but high-ROI, caching setup --
@@ -173,19 +175,16 @@ func get_beacon_committee*(state: BeaconState, slot: Slot, index: uint64, cache:
     cache.active_validator_indices_cache[epoch] =
       get_active_validator_indices(state, epoch)
 
-  if epoch notin cache.committee_count_cache:
-    cache.committee_count_cache[epoch] = get_committee_count(state, epoch)
+  # TODO remove or replace this...
+  #if epoch notin cache.committee_count_cache:
+  #  cache.committee_count_cache[epoch] = get_committee_count(state, epoch)
 
   # TODO profiling & make sure caches populated
   compute_committee(
     cache.active_validator_indices_cache[epoch],
     get_seed(state, epoch, DOMAIN_BEACON_ATTESTER),
     (slot mod SLOTS_PER_EPOCH) * committees_per_slot + index,
-
-    # TODO switch to 0.9's
-    # committees_per_slot * SLOTS_PER_EPOCH,
-    cache.committee_count_cache[epoch],
-
+    committees_per_slot * SLOTS_PER_EPOCH,
     cache
   )
 
diff --git a/research/state_sim.nim b/research/state_sim.nim
index 7d5a1204f..eaf14b974 100644
--- a/research/state_sim.nim
+++ b/research/state_sim.nim
@@ -97,7 +97,8 @@ cli do(slots = 448'u,
         epoch = compute_epoch_at_slot(state.slot)
         scass = withTimerRet(timers[tShuffle]):
           mapIt(
-            0'u64 .. (get_committee_count(state, epoch) - 1),
+            0'u64 .. (get_committee_count_at_slot(state, state.slot) *
+              SLOTS_PER_EPOCH - 1),
             get_crosslink_committee(state, epoch,
               (it + get_start_shard(state, epoch)) mod SHARD_COUNT,
               cache))
diff --git a/tests/mocking/mock_attestations.nim b/tests/mocking/mock_attestations.nim
index 6eac376a8..db2b57566 100644
--- a/tests/mocking/mock_attestations.nim
+++ b/tests/mocking/mock_attestations.nim
@@ -108,7 +108,8 @@ proc mockAttestationImpl(
   let
     epoch = compute_epoch_at_slot(slot)
     epoch_start_shard = get_start_shard(state, epoch)
-    committees_per_slot = get_committee_count(state, epoch) div SLOTS_PER_EPOCH
+    committees_per_slot = get_committee_count_at_slot(
+      state, epoch.compute_start_slot_at_epoch)
     shard = (
       epoch_start_shard +
       committees_per_slot * (slot mod SLOTS_PER_EPOCH)
diff --git a/tests/spec_epoch_processing/justification_finalization_helpers.nim b/tests/spec_epoch_processing/justification_finalization_helpers.nim
index bb1c6508f..0d1866b9e 100644
--- a/tests/spec_epoch_processing/justification_finalization_helpers.nim
+++ b/tests/spec_epoch_processing/justification_finalization_helpers.nim
@@ -22,7 +22,7 @@ iterator getShardsForSlot(state: BeaconState, slot: Slot): Shard =
   let
     epoch = compute_epoch_at_slot(slot)
     epoch_start_shard = get_start_shard(state, epoch)
-    committees_per_slot = get_committee_count(state, epoch) div SLOTS_PER_EPOCH
+    committees_per_slot = get_committee_count_at_slot(state, slot)
     shard = epoch_start_shard + committees_per_slot * (slot mod SLOTS_PER_EPOCH)
 
   for i in 0 ..< committees_per_slot.int:
diff --git a/tests/testutil.nim b/tests/testutil.nim
index b875fb3d9..7c56b1125 100644
--- a/tests/testutil.nim
+++ b/tests/testutil.nim
@@ -161,7 +161,8 @@ proc find_shard_committee(
     state: BeaconState, validator_index: ValidatorIndex): auto =
   let epoch = compute_epoch_at_slot(state.slot)
   var cache = get_empty_per_epoch_cache()
-  for shard in 0'u64 ..< get_committee_count(state, epoch):
+  for shard in 0'u64 ..< get_committee_count_at_slot(
+      state, epoch.compute_start_slot_at_epoch) * SLOTS_PER_EPOCH:
     let committee = get_crosslink_committee(state, epoch,
       (shard + get_start_shard(state, epoch)) mod SHARD_COUNT, cache)
     if validator_index in committee:
diff --git a/tests/transition_0_9_0.nim b/tests/transition_0_9_0.nim
deleted file mode 100644
index 3ee3bf04b..000000000
--- a/tests/transition_0_9_0.nim
+++ /dev/null
@@ -1,15 +0,0 @@
-import
-  official/test_fixture_bls,
-  official/test_fixture_operations_attester_slashings,
-  official/test_fixture_operations_proposer_slashings,
-  official/test_fixture_shuffling,
-  official/test_fixture_operations_block_header,
-  official/test_fixture_sanity_blocks,
-  official/test_fixture_ssz_generic_types,
-  official/test_fixture_sanity_slots,
-  official/test_fixture_operations_voluntary_exit,
-  official/test_fixture_ssz_uint,
-  official/test_fixture_operations_deposits,
-  spec_block_processing/test_process_attestation,
-  spec_block_processing/test_process_deposits,
-  spec_epoch_processing/test_process_justification_and_finalization