diff --git a/pallas-utxorpc/Cargo.toml b/pallas-utxorpc/Cargo.toml
index c3f280e..cd3e403 100644
--- a/pallas-utxorpc/Cargo.toml
+++ b/pallas-utxorpc/Cargo.toml
@@ -15,10 +15,12 @@ pallas-traverse = { version = "=0.29.0", path = "../pallas-traverse" }
 pallas-primitives = { version = "=0.29.0", path = "../pallas-primitives" }
 pallas-codec = { version = "=0.29.0", path = "../pallas-codec" }
 pallas-crypto = { version = "=0.29.0", path = "../pallas-crypto" }
-
 utxorpc-spec = { version = "0.9.0" }
 prost-types = "0.13.1"
 
+# TODO: remove this dep once we have multiera params in traverse
+pallas-applying = { version = "=0.29.0", path = "../pallas-applying" }
+
 [dev-dependencies]
 hex = "0.4.3"
 serde_json = "1.0.120"
diff --git a/pallas-utxorpc/src/lib.rs b/pallas-utxorpc/src/lib.rs
index 1f552f4..47654d3 100644
--- a/pallas-utxorpc/src/lib.rs
+++ b/pallas-utxorpc/src/lib.rs
@@ -12,6 +12,8 @@ pub use utxorpc_spec::utxorpc::v1alpha as spec;
 
 use utxorpc_spec::utxorpc::v1alpha::cardano as u5c;
 
+mod params;
+
 pub type TxHash = Hash<32>;
 pub type TxoIndex = u32;
 pub type TxoRef = (TxHash, TxoIndex);
@@ -26,14 +28,14 @@ pub trait LedgerContext: Clone {
 #[derive(Default, Clone)]
 pub struct Mapper<C: LedgerContext> {
     ledger: Option<C>,
-    mask: FieldMask,
+    _mask: FieldMask,
 }
 
 impl<C: LedgerContext> Mapper<C> {
     pub fn new(ledger: C) -> Self {
         Self {
             ledger: Some(ledger),
-            mask: FieldMask { paths: vec![] },
+            _mask: FieldMask { paths: vec![] },
         }
     }
 
@@ -41,7 +43,7 @@ impl<C: LedgerContext> Mapper<C> {
     pub fn masked(&self, mask: FieldMask) -> Self {
         Self {
             ledger: self.ledger.clone(),
-            mask,
+            _mask: mask,
         }
     }
 }
diff --git a/pallas-utxorpc/src/params.rs b/pallas-utxorpc/src/params.rs
new file mode 100644
index 0000000..8e19ae6
--- /dev/null
+++ b/pallas-utxorpc/src/params.rs
@@ -0,0 +1,151 @@
+use pallas_applying::MultiEraProtocolParameters;
+use utxorpc_spec::utxorpc::v1alpha::cardano::{self as u5c, CostModel};
+
+use crate::{LedgerContext, Mapper};
+
+impl<C: LedgerContext> Mapper<C> {
+    pub fn map_pparams(&self, pparams: MultiEraProtocolParameters) -> u5c::PParams {
+        match pparams {
+            MultiEraProtocolParameters::Alonzo(params) => u5c::PParams {
+                max_tx_size: params.max_transaction_size.into(),
+                max_block_body_size: params.max_block_body_size.into(),
+                max_block_header_size: params.max_block_header_size.into(),
+                min_fee_coefficient: params.minfee_a.into(),
+                min_fee_constant: params.minfee_b.into(),
+                coins_per_utxo_byte: params.ada_per_utxo_byte,
+                stake_key_deposit: params.key_deposit,
+                pool_deposit: params.pool_deposit,
+                desired_number_of_pools: params.desired_number_of_stake_pools.into(),
+                pool_influence: Some(u5c::RationalNumber {
+                    numerator: params.pool_pledge_influence.numerator as i32,
+                    denominator: params.pool_pledge_influence.denominator as u32,
+                }),
+                monetary_expansion: Some(u5c::RationalNumber {
+                    numerator: params.expansion_rate.numerator as i32,
+                    denominator: params.expansion_rate.denominator as u32,
+                }),
+                treasury_expansion: Some(u5c::RationalNumber {
+                    numerator: params.treasury_growth_rate.numerator as i32,
+                    denominator: params.treasury_growth_rate.denominator as u32,
+                }),
+                min_pool_cost: params.min_pool_cost,
+                protocol_version: Some(u5c::ProtocolVersion {
+                    major: params.protocol_version.0 as u32,
+                    minor: params.protocol_version.1 as u32,
+                }),
+                max_value_size: params.max_value_size.into(),
+                collateral_percentage: params.collateral_percentage.into(),
+                max_collateral_inputs: params.max_collateral_inputs.into(),
+                max_execution_units_per_transaction: Some(u5c::ExUnits {
+                    memory: params.max_tx_ex_units.mem,
+                    steps: params.max_tx_ex_units.steps,
+                }),
+                max_execution_units_per_block: Some(u5c::ExUnits {
+                    memory: params.max_block_ex_units.mem,
+                    steps: params.max_block_ex_units.steps,
+                }),
+                cost_models: u5c::CostModels {
+                    // Only plutusv1.
+                    plutus_v1: params
+                        .cost_models_for_script_languages
+                        .first()
+                        .map(|(_, data)| CostModel {
+                            values: data.to_vec(),
+                        }),
+                    ..Default::default()
+                }
+                .into(),
+                ..Default::default()
+            },
+            MultiEraProtocolParameters::Shelley(params) => u5c::PParams {
+                max_tx_size: params.max_transaction_size.into(),
+                max_block_body_size: params.max_block_body_size.into(),
+                max_block_header_size: params.max_block_header_size.into(),
+                min_fee_coefficient: params.minfee_a.into(),
+                min_fee_constant: params.minfee_b.into(),
+                stake_key_deposit: params.key_deposit,
+                pool_deposit: params.pool_deposit,
+                desired_number_of_pools: params.desired_number_of_stake_pools.into(),
+                pool_influence: Some(u5c::RationalNumber {
+                    numerator: params.pool_pledge_influence.numerator as i32,
+                    denominator: params.pool_pledge_influence.denominator as u32,
+                }),
+                monetary_expansion: Some(u5c::RationalNumber {
+                    numerator: params.expansion_rate.numerator as i32,
+                    denominator: params.expansion_rate.denominator as u32,
+                }),
+                treasury_expansion: Some(u5c::RationalNumber {
+                    numerator: params.treasury_growth_rate.numerator as i32,
+                    denominator: params.treasury_growth_rate.denominator as u32,
+                }),
+                min_pool_cost: params.min_pool_cost,
+                protocol_version: Some(u5c::ProtocolVersion {
+                    major: params.protocol_version.0 as u32,
+                    minor: params.protocol_version.1 as u32,
+                }),
+                ..Default::default()
+            },
+            MultiEraProtocolParameters::Babbage(params) => u5c::PParams {
+                max_tx_size: params.max_transaction_size.into(),
+                max_block_body_size: params.max_block_body_size.into(),
+                max_block_header_size: params.max_block_header_size.into(),
+                min_fee_coefficient: params.minfee_a.into(),
+                min_fee_constant: params.minfee_b.into(),
+                coins_per_utxo_byte: params.ada_per_utxo_byte,
+                stake_key_deposit: params.key_deposit,
+                pool_deposit: params.pool_deposit,
+                desired_number_of_pools: params.desired_number_of_stake_pools.into(),
+                pool_influence: Some(u5c::RationalNumber {
+                    numerator: params.pool_pledge_influence.numerator as i32,
+                    denominator: params.pool_pledge_influence.denominator as u32,
+                }),
+                monetary_expansion: u5c::RationalNumber {
+                    numerator: params.expansion_rate.numerator as i32,
+                    denominator: params.expansion_rate.denominator as u32,
+                }
+                .into(),
+                treasury_expansion: Some(u5c::RationalNumber {
+                    numerator: params.treasury_growth_rate.numerator as i32,
+                    denominator: params.treasury_growth_rate.denominator as u32,
+                }),
+                min_pool_cost: params.min_pool_cost,
+                protocol_version: u5c::ProtocolVersion {
+                    major: params.protocol_version.0 as u32,
+                    minor: params.protocol_version.1 as u32,
+                }
+                .into(),
+                max_value_size: params.max_value_size.into(),
+                collateral_percentage: params.collateral_percentage.into(),
+                max_collateral_inputs: params.max_collateral_inputs.into(),
+                max_execution_units_per_transaction: Some(u5c::ExUnits {
+                    memory: params.max_tx_ex_units.mem,
+                    steps: params.max_tx_ex_units.steps,
+                }),
+                max_execution_units_per_block: Some(u5c::ExUnits {
+                    memory: params.max_block_ex_units.mem,
+                    steps: params.max_block_ex_units.steps,
+                }),
+                cost_models: u5c::CostModels {
+                    plutus_v1: params
+                        .cost_models_for_script_languages
+                        .plutus_v1
+                        .map(|values| u5c::CostModel { values }),
+                    plutus_v2: params
+                        .cost_models_for_script_languages
+                        .plutus_v2
+                        .map(|values| u5c::CostModel { values }),
+                }
+                .into(),
+                ..Default::default()
+            },
+            MultiEraProtocolParameters::Byron(params) => u5c::PParams {
+                max_tx_size: params.max_tx_size,
+                max_block_body_size: params.max_block_size - params.max_header_size,
+                max_block_header_size: params.max_header_size,
+                ..Default::default()
+            },
+
+            _ => unimplemented!(),
+        }
+    }
+}