diff --git a/src/bin/git-add-coauthor.rs b/src/bin/git-add-coauthor.rs
new file mode 100644
index 0000000..2e5afb7
--- /dev/null
+++ b/src/bin/git-add-coauthor.rs
@@ -0,0 +1,24 @@
+use git_mob::{Author, get_available_coauthors, write_coauthors_file} ;
+use structopt::StructOpt;
+
+#[derive(StructOpt,Debug)]
+struct Opt {
+    /// Co-author initials
+    initials: String,
+    /// The name of the co-author, in quotes, e.g. "Foo Bar"
+    name: String,
+    /// The email of the co-author
+    email: String,
+}
+
+fn main() {
+    let opt = Opt::from_args();
+    let mut authors = get_available_coauthors();
+    let new_author = Author {
+        name: opt.name,
+        email: opt.email,
+    };
+    authors.insert(opt.initials, new_author);
+
+    write_coauthors_file(authors);
+}
diff --git a/src/lib.rs b/src/lib.rs
index 9c13318..19e6426 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,4 +1,5 @@
 use serde::{Deserialize, Serialize};
+use std::fs;
 use git2::{Config, Repository};
 use std::fmt;
 use std::collections::BTreeMap;
@@ -12,8 +13,8 @@ use std::process;
 
 #[derive(Serialize, Deserialize, Clone, Debug)]
 pub struct Author {
-    name: String,
-    email: String,
+    pub name: String,
+    pub email: String,
 }
 
 impl fmt::Display for Author {
@@ -44,7 +45,7 @@ pub fn get_available_coauthors() -> BTreeMap<String, Author> {
 }
 
 fn parse_coauthors_file() -> Result<BTreeMap<String, Author>, Box<dyn Error>> {
-    let coauthors_path = home_dir().unwrap().join(".git-coauthors");
+    let coauthors_path = coauthors_file_path();
     let coauthors_file = File::open(coauthors_path)?;
     let reader = BufReader::new(coauthors_file);
 
@@ -69,3 +70,20 @@ pub fn with_repo_or_exit<F: FnOnce(Repository)>(f: F) {
         }
     }
 }
+
+pub fn write_coauthors_file(authors: BTreeMap<String, Author>) {
+    let mut wrapper_tree = BTreeMap::new();
+    wrapper_tree.insert("coauthors", authors);
+    let json_data = serde_json::to_string_pretty(&wrapper_tree).unwrap();
+    match fs::write(coauthors_file_path(), json_data) {
+        Ok(_) => {},
+        Err(e) => {
+            eprintln!("Error writing git-coauthors file: {:?}", e);
+            process::exit(1);
+        }
+    }
+}
+
+fn coauthors_file_path() -> std::path::PathBuf {
+    home_dir().unwrap().join(".git-coauthors")
+}