diff --git a/validator_client/src/attestation_service.rs b/validator_client/src/attestation_service.rs
new file mode 100644
index 0000000000..a7b881b53d
--- /dev/null
+++ b/validator_client/src/attestation_service.rs
@@ -0,0 +1,245 @@
+use crate::{
+    duties_service::DutiesService, fork_service::ForkService, validator_store::ValidatorStore,
+};
+use environment::RuntimeContext;
+use exit_future::Signal;
+use futures::{stream, Future, IntoFuture, Stream};
+use remote_beacon_node::{PublishStatus, RemoteBeaconNode};
+use slog::{error, info, trace, warn};
+use slot_clock::SlotClock;
+use std::sync::Arc;
+use std::time::{Duration, Instant};
+use tokio::timer::Interval;
+use types::{ChainSpec, EthSpec};
+
+/// Delay this period of time after the slot starts. This allows the node to process the new slot.
+const TIME_DELAY_FROM_SLOT: Duration = Duration::from_millis(100);
+
+#[derive(Clone)]
+pub struct AttestationServiceBuilder<T: Clone, E: EthSpec> {
+    fork_service: Option<ForkService<T, E>>,
+    duties_service: Option<DutiesService<T, E>>,
+    validator_store: Option<ValidatorStore<E>>,
+    slot_clock: Option<Arc<T>>,
+    beacon_node: Option<RemoteBeaconNode<E>>,
+    context: Option<RuntimeContext<E>>,
+}
+
+// TODO: clean trait bounds.
+impl<T: SlotClock + Clone + 'static, E: EthSpec> AttestationServiceBuilder<T, E> {
+    pub fn new() -> Self {
+        Self {
+            fork_service: None,
+            duties_service: None,
+            validator_store: None,
+            slot_clock: None,
+            beacon_node: None,
+            context: None,
+        }
+    }
+
+    pub fn fork_service(mut self, service: ForkService<T, E>) -> Self {
+        self.fork_service = Some(service);
+        self
+    }
+
+    pub fn duties_service(mut self, service: DutiesService<T, E>) -> Self {
+        self.duties_service = Some(service);
+        self
+    }
+
+    pub fn validator_store(mut self, store: ValidatorStore<E>) -> Self {
+        self.validator_store = Some(store);
+        self
+    }
+
+    pub fn slot_clock(mut self, slot_clock: T) -> Self {
+        self.slot_clock = Some(Arc::new(slot_clock));
+        self
+    }
+
+    pub fn beacon_node(mut self, beacon_node: RemoteBeaconNode<E>) -> Self {
+        self.beacon_node = Some(beacon_node);
+        self
+    }
+
+    pub fn runtime_context(mut self, context: RuntimeContext<E>) -> Self {
+        self.context = Some(context);
+        self
+    }
+
+    pub fn build(self) -> Result<AttestationService<T, E>, String> {
+        Ok(AttestationService {
+            fork_service: self
+                .fork_service
+                .ok_or_else(|| "Cannot build AttestationService without fork_service")?,
+            duties_service: self
+                .duties_service
+                .ok_or_else(|| "Cannot build AttestationService without duties_service")?,
+            validator_store: self
+                .validator_store
+                .ok_or_else(|| "Cannot build AttestationService without validator_store")?,
+            slot_clock: self
+                .slot_clock
+                .ok_or_else(|| "Cannot build AttestationService without slot_clock")?,
+            beacon_node: self
+                .beacon_node
+                .ok_or_else(|| "Cannot build AttestationService without beacon_node")?,
+            context: self
+                .context
+                .ok_or_else(|| "Cannot build AttestationService without runtime_context")?,
+        })
+    }
+}
+
+#[derive(Clone)]
+pub struct AttestationService<T: Clone, E: EthSpec> {
+    duties_service: DutiesService<T, E>,
+    fork_service: ForkService<T, E>,
+    validator_store: ValidatorStore<E>,
+    slot_clock: Arc<T>,
+    beacon_node: RemoteBeaconNode<E>,
+    context: RuntimeContext<E>,
+}
+
+// TODO: clean trait bounds.
+impl<T: SlotClock + Clone + 'static, E: EthSpec> AttestationService<T, E> {
+    pub fn start_update_service(&self, spec: &ChainSpec) -> Result<Signal, String> {
+        let log = self.context.log.clone();
+
+        let duration_to_next_slot = self
+            .slot_clock
+            .duration_to_next_slot()
+            .ok_or_else(|| "Unable to determine duration to next slot".to_string())?;
+
+        let interval = {
+            let slot_duration = Duration::from_millis(spec.milliseconds_per_slot);
+            Interval::new(
+                Instant::now() + duration_to_next_slot + TIME_DELAY_FROM_SLOT,
+                slot_duration,
+            )
+        };
+
+        info!(
+            log,
+            "Waiting for next slot";
+            "seconds_to_wait" => duration_to_next_slot.as_secs()
+        );
+
+        let (exit_signal, exit_fut) = exit_future::signal();
+        let service = self.clone();
+
+        self.context.executor.spawn(
+            interval
+                .map_err(move |e| {
+                    error! {
+                        log,
+                        "Timer thread failed";
+                        "error" => format!("{}", e)
+                    }
+                })
+                .and_then(move |_| if exit_fut.is_live() { Ok(()) } else { Err(()) })
+                .for_each(move |_| service.clone().do_update()),
+        );
+
+        Ok(exit_signal)
+    }
+
+    fn do_update(self) -> impl Future<Item = (), Error = ()> {
+        let service = self.clone();
+        let log = self.context.log.clone();
+
+        self.slot_clock
+            .now()
+            .ok_or_else(move || {
+                error!(log, "Duties manager failed to read slot clock");
+            })
+            .into_future()
+            .and_then(move |slot| {
+                let iter = service.duties_service.block_producers(slot).into_iter();
+
+                stream::unfold(iter, move |mut block_producers| {
+                    let log_1 = service.context.log.clone();
+                    let log_2 = service.context.log.clone();
+                    let service_1 = service.clone();
+                    let service_2 = service.clone();
+                    let service_3 = service.clone();
+
+                    block_producers.next().map(move |validator_pubkey| {
+                        service_2
+                            .fork_service
+                            .fork()
+                            .ok_or_else(|| "Fork is unknown, unable to sign".to_string())
+                            .and_then(|fork| {
+                                service_1
+                                    .validator_store
+                                    .randao_reveal(
+                                        &validator_pubkey,
+                                        slot.epoch(E::slots_per_epoch()),
+                                        &fork,
+                                    )
+                                    .map(|randao_reveal| (fork, randao_reveal))
+                                    .ok_or_else(|| "Unable to produce randao reveal".to_string())
+                            })
+                            .into_future()
+                            .and_then(move |(fork, randao_reveal)| {
+                                service_1
+                                    .beacon_node
+                                    .http
+                                    .validator()
+                                    .produce_block(slot, randao_reveal)
+                                    .map(|block| (fork, block))
+                                    .map_err(|e| {
+                                        format!(
+                                            "Error from beacon node when producing block: {:?}",
+                                            e
+                                        )
+                                    })
+                            })
+                            .and_then(move |(fork, block)| {
+                                service_2
+                                    .validator_store
+                                    .sign_block(&validator_pubkey, block, &fork)
+                                    .ok_or_else(|| "Unable to sign block".to_string())
+                            })
+                            .and_then(move |block| {
+                                service_3
+                                    .beacon_node
+                                    .http
+                                    .validator()
+                                    .publish_block(block)
+                                    .map_err(|e| {
+                                        format!(
+                                            "Error from beacon node when publishing block: {:?}",
+                                            e
+                                        )
+                                    })
+                            })
+                            .map(move |publish_outcome| match publish_outcome {
+                                PublishStatus::Valid => {
+                                    info!(log_1, "Successfully published block")
+                                }
+                                PublishStatus::Invalid(msg) => error!(
+                                    log_1,
+                                    "Published block was invalid";
+                                    "message" => msg
+                                ),
+                                PublishStatus::Unknown => {
+                                    info!(log_1, "Unknown condition when publishing block")
+                                }
+                            })
+                            .map_err(move |e| {
+                                error!(
+                                    log_2,
+                                    "Error whilst producing block";
+                                    "message" => e
+                                )
+                            })
+                            .then(|_| Ok(((), block_producers)))
+                    })
+                })
+                .collect()
+                .map(|_| ())
+            })
+    }
+}
diff --git a/validator_client/src/duties_service.rs b/validator_client/src/duties_service.rs
index 8d3f24b783..5937d66a4f 100644
--- a/validator_client/src/duties_service.rs
+++ b/validator_client/src/duties_service.rs
@@ -10,7 +10,7 @@ use std::collections::HashMap;
 use std::sync::Arc;
 use std::time::{Duration, Instant};
 use tokio::timer::Interval;
-use types::{ChainSpec, Epoch, EthSpec, PublicKey, Slot};
+use types::{ChainSpec, CommitteeIndex, Epoch, EthSpec, PublicKey, Slot};
 
 /// Delay this period of time after the slot starts. This allows the node to process the new slot.
 const TIME_DELAY_FROM_SLOT: Duration = Duration::from_millis(100);
@@ -36,6 +36,8 @@ impl DutiesStore {
             // As long as a `HashMap` iterator does not return duplicate keys, neither will this
             // function.
             .filter(|(_validator_pubkey, validator_map)| {
+                // TODO: it would be more efficient to call the `validator_map` by key (epoch)
+                // instead of searching for slots.
                 validator_map.iter().any(|(_epoch, duties)| {
                     duties
                         .block_proposal_slot
@@ -48,6 +50,27 @@ impl DutiesStore {
             .collect()
     }
 
+    fn attesters(&self, slot: Slot) -> Vec<ValidatorDuty> {
+        self.store
+            .read()
+            .iter()
+            .filter_map(|(_validator_pubkey, validator_map)| {
+                validator_map
+                    // TODO: it would be more efficient to call the `validator_map` by key (epoch)
+                    // instead of searching for slots.
+                    .iter()
+                    .find(|(_epoch, duties)| {
+                        duties
+                            .attestation_slot
+                            .map(|s| s == slot)
+                            .unwrap_or_else(|| false)
+                    })
+                    .map(|(_epoch, duties)| duties)
+            })
+            .cloned()
+            .collect()
+    }
+
     fn insert(&self, epoch: Epoch, duties: ValidatorDuty) -> InsertOutcome {
         let mut store = self.store.write();
 
@@ -177,6 +200,11 @@ impl<T: SlotClock + Clone + 'static, E: EthSpec> DutiesService<T, E> {
         self.store.block_producers(slot)
     }
 
+    /// Returns all `ValidatorDuty` for the given `slot`.
+    pub fn attesters(&self, slot: Slot) -> Vec<ValidatorDuty> {
+        self.store.attesters(slot)
+    }
+
     pub fn start_update_service(&self, spec: &ChainSpec) -> Result<Signal, String> {
         let log = self.context.log.clone();
 
diff --git a/validator_client/src/lib.rs b/validator_client/src/lib.rs
index 6f1c1b3371..587de74e32 100644
--- a/validator_client/src/lib.rs
+++ b/validator_client/src/lib.rs
@@ -1,3 +1,4 @@
+mod attestation_service;
 mod block_service;
 mod cli;
 mod config;