diff --git a/crates/aiken-project/src/blueprint/validator.rs b/crates/aiken-project/src/blueprint/validator.rs
index 84e86645..18f230f9 100644
--- a/crates/aiken-project/src/blueprint/validator.rs
+++ b/crates/aiken-project/src/blueprint/validator.rs
@@ -129,14 +129,16 @@ impl<T> Validator<T>
 where
     T: Clone,
 {
-    pub fn apply(&mut self, arg: &Term<DeBruijn>) -> Result<(), Error> {
+    pub fn apply(self, arg: &Term<DeBruijn>) -> Result<Self, Error> {
         match self.parameters.split_first() {
             None => Err(Error::NoParametersToApply),
             Some((_, tail)) => {
                 // TODO: Ideally, we should control that the applied term matches its schema.
-                self.program = self.program.apply_term(arg);
-                self.parameters = tail.to_vec();
-                Ok(())
+                Ok(Self {
+                    program: self.program.apply_term(arg),
+                    parameters: tail.to_vec(),
+                    ..self
+                })
             }
         }
     }
diff --git a/crates/aiken-project/src/lib.rs b/crates/aiken-project/src/lib.rs
index 5f79b988..d54c2ff4 100644
--- a/crates/aiken-project/src/lib.rs
+++ b/crates/aiken-project/src/lib.rs
@@ -331,20 +331,32 @@ where
         // Read blueprint
         let blueprint = File::open(self.blueprint_path())
             .map_err(|_| blueprint::error::Error::InvalidOrMissingFile)?;
-        let blueprint: Blueprint<serde_json::Value> =
+        let mut blueprint: Blueprint<serde_json::Value> =
             serde_json::from_reader(BufReader::new(blueprint))?;
 
         // Apply parameters
         let when_too_many =
             |known_validators| Error::MoreThanOneValidatorFound { known_validators };
         let when_missing = |known_validators| Error::NoValidatorNotFound { known_validators };
-        blueprint.with_validator(
-            title,
-            purpose,
-            when_too_many,
-            when_missing,
-            |mut validator| validator.apply(param).map_err(|e| e.into()),
-        )?;
+        let applied_validator =
+            blueprint.with_validator(title, purpose, when_too_many, when_missing, |validator| {
+                validator.apply(param).map_err(|e| e.into())
+            })?;
+
+        // Overwrite validator
+        blueprint.validators = blueprint
+            .validators
+            .into_iter()
+            .map(|validator| {
+                let same_title = validator.title == applied_validator.title;
+                let same_purpose = validator.purpose == applied_validator.purpose;
+                if same_title && same_purpose {
+                    applied_validator.to_owned()
+                } else {
+                    validator
+                }
+            })
+            .collect();
 
         Ok(blueprint)
     }
diff --git a/crates/aiken/src/cmd/address.rs b/crates/aiken/src/cmd/blueprint/address.rs
similarity index 100%
rename from crates/aiken/src/cmd/address.rs
rename to crates/aiken/src/cmd/blueprint/address.rs
diff --git a/crates/aiken/src/cmd/blueprint/apply.rs b/crates/aiken/src/cmd/blueprint/apply.rs
new file mode 100644
index 00000000..6f290146
--- /dev/null
+++ b/crates/aiken/src/cmd/blueprint/apply.rs
@@ -0,0 +1,60 @@
+use crate::with_project;
+use aiken_lang::VALIDATOR_NAMES;
+use aiken_project::error::Error;
+use miette::IntoDiagnostic;
+use std::{fs, path::PathBuf};
+use uplc::{
+    ast::{DeBruijn, Term},
+    parser,
+};
+
+#[derive(clap::Args)]
+#[clap(setting(clap::AppSettings::DeriveDisplayOrder))]
+/// Apply a parameter to a parameterized validator.
+pub struct Args {
+    /// Path to project
+    directory: Option<PathBuf>,
+
+    /// Name of the validator's module within the project. Optional if there's only one validator.
+    #[clap(short, long)]
+    validator: Option<String>,
+
+    /// Purpose of the validator within the module. Optional if there's only one validator.
+    #[clap(short, long, possible_values=&VALIDATOR_NAMES)]
+    purpose: Option<String>,
+
+    /// The parameter, using high-level UPLC-syntax
+    #[clap(long)]
+    parameter: String,
+}
+
+pub fn exec(
+    Args {
+        directory,
+        validator,
+        purpose,
+        parameter,
+    }: Args,
+) -> miette::Result<()> {
+    let term: Term<DeBruijn> = parser::term(&parameter)
+        .into_diagnostic()?
+        .try_into()
+        .into_diagnostic()?;
+
+    with_project(directory, |p| {
+        let blueprint = p.apply_parameter(
+            validator.as_ref(),
+            purpose
+                .as_ref()
+                .map(|p| p.clone().try_into().unwrap())
+                .as_ref(),
+            &term,
+        )?;
+
+        let json = serde_json::to_string_pretty(&blueprint).unwrap();
+        fs::write(p.blueprint_path(), json).map_err(|error| Error::FileIo {
+            error,
+            path: p.blueprint_path(),
+        })
+    })
+}
diff --git a/crates/aiken/src/cmd/blueprint/mod.rs b/crates/aiken/src/cmd/blueprint/mod.rs
new file mode 100644
index 00000000..0dde4d8a
--- /dev/null
+++ b/crates/aiken/src/cmd/blueprint/mod.rs
@@ -0,0 +1,19 @@
+pub mod address;
+pub mod apply;
+
+use clap::Subcommand;
+
+/// Commands for working with Plutus blueprints
+#[derive(Subcommand)]
+#[clap(setting(clap::AppSettings::DeriveDisplayOrder))]
+pub enum Cmd {
+    Address(address::Args),
+    Apply(apply::Args),
+}
+
+pub fn exec(cmd: Cmd) -> miette::Result<()> {
+    match cmd {
+        Cmd::Address(args) => address::exec(args),
+        Cmd::Apply(args) => apply::exec(args),
+    }
+}
diff --git a/crates/aiken/src/cmd/mod.rs b/crates/aiken/src/cmd/mod.rs
index 1f69dae9..bfef865e 100644
--- a/crates/aiken/src/cmd/mod.rs
+++ b/crates/aiken/src/cmd/mod.rs
@@ -1,4 +1,4 @@
-pub mod address;
+pub mod blueprint;
 pub mod build;
 pub mod check;
 pub mod docs;
diff --git a/crates/aiken/src/main.rs b/crates/aiken/src/main.rs
index 597f134a..f3bc0fc4 100644
--- a/crates/aiken/src/main.rs
+++ b/crates/aiken/src/main.rs
@@ -1,5 +1,6 @@
 use aiken::cmd::{
-    address, build, check, docs, fmt, lsp, new,
+    blueprint::{self, address},
+    build, check, docs, fmt, lsp, new,
     packages::{self, add},
     tx, uplc,
 };
@@ -19,6 +20,9 @@ pub enum Cmd {
     Docs(docs::Args),
     Add(add::Args),
 
+    #[clap(subcommand)]
+    Blueprint(blueprint::Cmd),
+
     #[clap(subcommand)]
     Packages(packages::Cmd),
 
@@ -48,6 +52,7 @@ fn main() -> miette::Result<()> {
         Cmd::Check(args) => check::exec(args),
         Cmd::Docs(args) => docs::exec(args),
         Cmd::Add(args) => add::exec(args),
+        Cmd::Blueprint(args) => blueprint::exec(args),
         Cmd::Packages(args) => packages::exec(args),
         Cmd::Lsp(args) => lsp::exec(args),
         Cmd::Tx(sub_cmd) => tx::exec(sub_cmd),