diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0bcfcb95dc..2b595e04af 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 ### Changed
+- Added centralized documentation for environment variables in use by Holochain [PR](https://github.com/holochain/holochain-rust/pull/990)
 - Added command `hc keygen` which creates a new key pair, asks for a passphrase and writes an encrypted key bundle file to `~/.holochain/keys`.
 - `hash` properties for `UiBundleConfiguration` and `DnaConfiguration` in Conductor config files is now optional
 - core now depends on `pretty_assertions` crate
diff --git a/cli/src/cli/run.rs b/cli/src/cli/run.rs
index 38bf6ecb81..69c09f1463 100644
--- a/cli/src/cli/run.rs
+++ b/cli/src/cli/run.rs
@@ -1,13 +1,14 @@
 use cli::{self, package};
 use colored::*;
 use error::DefaultResult;
+use holochain_common::env_vars::EnvVar;
 use holochain_conductor_api::{
     conductor::{mount_conductor_from_config, CONDUCTOR},
     config::*,
     logger::LogRules,
 };
 use holochain_core_types::agent::AgentId;
-use std::{env, fs};
+use std::fs;
 
 const LOCAL_STORAGE_PATH: &str = ".hc";
 
@@ -16,7 +17,7 @@ const DNA_CONFIG_ID: &str = "hc-run-dna";
 const INSTANCE_CONFIG_ID: &str = "test-instance";
 const INTERFACE_CONFIG_ID: &str = "websocket-interface";
 
-/// Starts a small conductor with the current application running
+/// Starts a minimal configuration Conductor with the current application running
 pub fn run(
     package: bool,
     port: u16,
@@ -28,7 +29,10 @@ pub fn run(
         cli::package(true, Some(package::DEFAULT_BUNDLE_FILE_NAME.into()))?;
     }
 
-    let agent_name = env::var("HC_AGENT").ok();
+    // note that this behaviour is documented within
+    // holochain_common::env_vars module and should be updated
+    // if this logic changes
+    let agent_name = EnvVar::value(&EnvVar::Agent).ok();
     let agent = AgentId::generate_fake(&agent_name.unwrap_or_else(|| String::from("testAgent")));
     let agent_config = AgentConfiguration {
         id: AGENT_CONFIG_ID.into(),
@@ -60,7 +64,12 @@ pub fn run(
         storage,
     };
 
-    let interface_type = env::var("HC_INTERFACE").ok().unwrap_or_else(|| interface);
+    // note that this behaviour is documented within
+    // holochain_common::env_vars module and should be updated
+    // if this logic changes
+    let interface_type = EnvVar::value(&EnvVar::Interface)
+        .ok()
+        .unwrap_or_else(|| interface);
     let driver = if interface_type == String::from("websocket") {
         InterfaceDriver::Websocket { port }
     } else if interface_type == String::from("http") {
@@ -85,15 +94,21 @@ pub fn run(
         rules,
     };
 
-    let n3h_path = env::var("HC_N3H_PATH").ok();
+    // note that this behaviour is documented within
+    // holochain_common::env_vars module and should be updated
+    // if this logic changes
+    let n3h_path = EnvVar::value(&EnvVar::N3hPath).ok();
 
     // create an n3h network config if the --networked flag is set
     // or if a value where to find n3h has been put into the
     // HC_N3H_PATH environment variable
     let network_config = if networked || n3h_path.is_some() {
-        let n3h_mode = env::var("HC_N3H_MODE").ok();
-        let n3h_persistence_path = env::var("HC_N3H_WORK_DIR").ok();
-        let n3h_bootstrap_node = env::var("HC_N3H_BOOTSTRAP_NODE").ok();
+        // note that this behaviour is documented within
+        // holochain_common::env_vars module and should be updated
+        // if this logic changes
+        let n3h_mode = EnvVar::value(&EnvVar::N3hMode).ok();
+        let n3h_persistence_path = EnvVar::value(&EnvVar::N3hWorkDir).ok();
+        let n3h_bootstrap_node = EnvVar::value(&EnvVar::N3hBootstrapNode).ok();
         let mut n3h_bootstrap = Vec::new();
 
         if n3h_bootstrap_node.is_some() {
@@ -101,7 +116,10 @@ pub fn run(
         }
 
         // Load end_user config file
-        let networking_config_filepath = env::var("NETWORKING_CONFIG_FILE").ok();
+        // note that this behaviour is documented within
+        // holochain_common::env_vars module and should be updated
+        // if this logic changes
+        let networking_config_filepath = EnvVar::value(&EnvVar::NetworkingConfigFile).ok();
 
         Some(NetworkConfig {
             bootstrap_nodes: n3h_bootstrap,
diff --git a/common/src/env_vars.rs b/common/src/env_vars.rs
new file mode 100644
index 0000000000..1c4dfbfaee
--- /dev/null
+++ b/common/src/env_vars.rs
@@ -0,0 +1,57 @@
+//! Holochain uses a number of environment variables that can be set, for easy configuration for aspects of the system.
+//! Below is the complete list of them, and what they are used for.
+//!
+//! ### `hc run`
+//! Read more about the use of these environment variables [here](https://developer.holochain.org/guide/latest/hc_configuring_networking.html).
+//! - **HC_AGENT** *string* Set an alternative name for the agent for the development instance.
+//! Default value is `testAgent`.
+//! Useful for changing the agent while running multiple instances.
+//! - **HC_INTERFACE** *string* **websocket** OR **http** Set an interface type to use. Setting this as an environment variable will override the
+//! value of the `--interface` option for `hc run`. The default interface if neither is set is `websocket`.
+//! - **HC_N3H_PATH** *string* Path to the [n3h](https://github.com/holochain/n3h) networking module. If set, this will automatically trigger `hc run` to do live networking,
+//! instead of mock networking which is the default. The following environment variables are irrelevant if `hc run` is not run with the `--networked`
+//! flag, AND this is not set, because they are all configuration for live networking. Default is a subdirectory of your HOME folder, at the path `.hc/net/n3h`.
+//! - **HC_N3H_WORK_DIR** *string* Eventually, there will be a directory needed by n3h for persisting data, such as remote node QoS metrics, peer lists, and non-core DHT data items such as peer discovery info.
+//! Default is temporary directory which will get removed again once the Conductor process stops. Recommended not to use this at this time.
+//! - **HC_N3H_BOOTSTRAP_NODE** *string* Set an external p2p bound ip4 address for another node, to bootstrap the networking discovery process.
+//! Without this, a second node will of a network will be unable to find any others. See [configuring networking]([here](https://developer.holochain.org/guide/latest/hc_configuring_networking.html)
+//! for details.
+//! - **NETWORKING_CONFIG_FILE** *string* Path to a JSON file containing configuration for the n3h networking module. More on this soon. Recommended to
+//! not use this as this time.
+//!
+//! ### Other
+//! - **HC_SIMPLE_LOGGER_MUTE** *int* Setting this value to 1 will silence the log output of a SimpleLogger. Use with any Conductor.
+
+// TODO, add this back in once the only option isn't "HACK"
+// - **HC_N3H_MODE** *string* **HACK**
+
+use std::env::VarError;
+
+pub enum EnvVar {
+    Agent,
+    Interface,
+    N3hPath,
+    N3hMode,
+    N3hWorkDir,
+    N3hBootstrapNode,
+    NetworkingConfigFile,
+    SimpleLoggerMute,
+}
+
+impl EnvVar {
+    pub fn as_str(&self) -> &str {
+        match self {
+            EnvVar::Agent => "HC_AGENT",
+            EnvVar::Interface => "HC_INTERFACE",
+            EnvVar::N3hPath => "HC_N3H_PATH",
+            EnvVar::N3hMode => "HC_N3H_MODE",
+            EnvVar::N3hWorkDir => "HC_N3H_WORK_DIR",
+            EnvVar::N3hBootstrapNode => "HC_N3H_BOOTSTRAP_NODE",
+            EnvVar::NetworkingConfigFile => "NETWORKING_CONFIG_FILE",
+            EnvVar::SimpleLoggerMute => "HC_SIMPLE_LOGGER_MUTE",
+        }
+    }
+    pub fn value(&self) -> Result<String, VarError> {
+        std::env::var(self.as_str())
+    }
+}
diff --git a/common/src/lib.rs b/common/src/lib.rs
index 8118b2968e..13affa7aa3 100644
--- a/common/src/lib.rs
+++ b/common/src/lib.rs
@@ -1 +1,2 @@
+pub mod env_vars;
 pub mod paths;
diff --git a/conductor_api/src/config.rs b/conductor_api/src/config.rs
index d31615989d..6e60190686 100644
--- a/conductor_api/src/config.rs
+++ b/conductor_api/src/config.rs
@@ -466,10 +466,16 @@ pub struct NetworkConfig {
     pub networking_config_file: Option<String>,
 }
 
+// note that this behaviour is documented within
+// holochain_common::env_vars module and should be updated
+// if this logic changes
 pub fn default_n3h_mode() -> String {
     String::from("HACK")
 }
 
+// note that this behaviour is documented within
+// holochain_common::env_vars module and should be updated
+// if this logic changes
 pub fn default_n3h_path() -> String {
     if let Some(user_dirs) = directories::UserDirs::new() {
         user_dirs
@@ -484,6 +490,9 @@ pub fn default_n3h_path() -> String {
     }
 }
 
+// note that this behaviour is documented within
+// holochain_common::env_vars module and should be updated
+// if this logic changes
 pub fn default_n3h_persistence_path() -> String {
     env::temp_dir().to_string_lossy().to_string()
 }
diff --git a/core/Cargo.toml b/core/Cargo.toml
index 66ade5d38b..f130de5576 100644
--- a/core/Cargo.toml
+++ b/core/Cargo.toml
@@ -31,6 +31,7 @@ num-derive = "0.2"
 config = "0.8"
 regex = "1"
 toml = "0.4.8"
+holochain_common = { path = "../common" }
 holochain_core_types = { path = "../core_types" }
 holochain_core_types_derive = { path = "../core_types_derive" }
 holochain_cas_implementations = { path = "../cas_implementations" }
diff --git a/core/src/lib.rs b/core/src/lib.rs
index 73c04e8125..f5879099e9 100755
--- a/core/src/lib.rs
+++ b/core/src/lib.rs
@@ -23,6 +23,7 @@ extern crate num_traits;
 extern crate regex;
 
 extern crate config;
+extern crate holochain_common;
 extern crate holochain_net;
 #[macro_use]
 extern crate holochain_wasm_utils;
diff --git a/core/src/logger.rs b/core/src/logger.rs
index bee3056396..551df3e4ea 100644
--- a/core/src/logger.rs
+++ b/core/src/logger.rs
@@ -2,6 +2,7 @@
 //! which is separate from standard logging via the log crate warn! info! debug! logging that
 //! gets emitted globaly from the conductor.
 use chrono::Local;
+use holochain_common::env_vars::EnvVar;
 use std::sync::{mpsc, Arc, Mutex};
 
 /// trait that defines the logging functionality that holochain_core requires
@@ -21,7 +22,10 @@ pub struct SimpleLogger {
 #[cfg_attr(tarpaulin, skip)]
 impl Logger for SimpleLogger {
     fn log(&mut self, msg: String) {
-        if std::env::var("HC_SIMPLE_LOGGER_MUTE").is_err() {
+        // note that this behaviour is documented within
+        // holochain_common::env_vars module and should be updated
+        // if this logic changes
+        if EnvVar::value(&EnvVar::SimpleLoggerMute).is_err() {
             let date = Local::now();
             println!("{}:{}", date.format("%Y-%m-%d %H:%M:%S"), msg);
         }
diff --git a/wasm_utils/src/lib.rs b/wasm_utils/src/lib.rs
index 81e1b66799..e6cf783bf6 100644
--- a/wasm_utils/src/lib.rs
+++ b/wasm_utils/src/lib.rs
@@ -18,6 +18,8 @@ pub mod macros;
 pub mod memory;
 
 pub fn wasm_target_dir(test_path: &str, wasm_path: &str) -> String {
+    // this env var checker can't use holochain_common
+    // crate because that uses `directories` crate which doesn't compile to WASM
     match std::env::var("HC_TARGET_PREFIX") {
         Ok(prefix) => format!("{}{}{}target", prefix, test_path, wasm_path),
         Err(_) => format!("{}target", wasm_path),