diff --git a/Datastore/Sources/DatastoreClient.swift b/Datastore/Sources/DatastoreClient.swift
index b4dba00..0e793b6 100644
--- a/Datastore/Sources/DatastoreClient.swift
+++ b/Datastore/Sources/DatastoreClient.swift
@@ -26,12 +26,14 @@ public final class GoogleCloudDatastoreClient {
                                                                          eventLoop: eventLoop)
         
         /// Set the projectId to use for this client. In order of priority:
+        /// - Environment Variable (GOOGLE_PROJECT_ID) 
         /// - Environment Variable (PROJECT_ID)
         /// - Service Account's projectID
         /// - `GoogleCloudDatastoreConfigurations` `project` property (optionally configured).
         /// - `GoogleCloudCredentialsConfiguration's` `project` property (optionally configured).
         
-        guard let projectId = ProcessInfo.processInfo.environment["PROJECT_ID"] ??
+        guard let projectId = ProcessInfo.processInfo.environment["GOOGLE_PROJECT_ID"] ??
+                              ProcessInfo.processInfo.environment["PROJECT_ID"] ??
                               (refreshableToken as? OAuthServiceAccount)?.credentials.projectId ??
                               config.project ?? credentials.project else {
             throw GoogleCloudDatastoreError.projectIdMissing
diff --git a/Datastore/Sources/README.md b/Datastore/Sources/README.md
index e7384b3..3af5633 100644
--- a/Datastore/Sources/README.md
+++ b/Datastore/Sources/README.md
@@ -33,6 +33,7 @@ let gcs = try GoogleCloudDatastoreClient(credentials: credentialsConfiguration,
 
 ```
 The order of priority for which configured projectID the DatastoreClient will use is as follows:
+1. `$GOOGLE_PROJECT_ID` environment variable.
 1. `$PROJECT_ID` environment variable.
 2. The Service Accounts projectID (Service account configured via the credentials path in the credentials configuration).
 3. `GoogleCloudDatastoreConfiguration`'s `project` property.
diff --git a/PubSub/Sources/PubSubClient.swift b/PubSub/Sources/PubSubClient.swift
index 88021ce..a82d946 100644
--- a/PubSub/Sources/PubSubClient.swift
+++ b/PubSub/Sources/PubSubClient.swift
@@ -17,7 +17,8 @@ public final class GoogleCloudPubSubClient {
                                                                          withConfig: config,
                                                                          andClient: httpClient,
                                                                          eventLoop: eventLoop)
-        guard let projectId = ProcessInfo.processInfo.environment["PROJECT_ID"] ??
+        guard let projectId = ProcessInfo.processInfo.environment["GOOGLE_PROJECT_ID"] ??
+                              ProcessInfo.processInfo.environment["PROJECT_ID"] ??
                               (refreshableToken as? OAuthServiceAccount)?.credentials.projectId ??
                               config.project ?? credentials.project else {
             throw GoogleCloudPubSubError.projectIdMissing
diff --git a/README.md b/README.md
index 4d70cea..011986a 100644
--- a/README.md
+++ b/README.md
@@ -44,7 +44,7 @@ Now setup the configuration.
 Optionally, you can register an empty `GoogleCloudCredentialsConfiguration()` and configure the following environment variables:
 
 ```shell
-export PROJECT_ID=myprojectid-12345
+export GOOGLE_PROJECT_ID=myprojectid-12345
 export GOOGLE_APPLICATION_CREDENTIALS=/path/to/your/service-account.json
 ```
 
diff --git a/SecretManager/Sources/README.md b/SecretManager/Sources/README.md
index 6ca015e..b439326 100644
--- a/SecretManager/Sources/README.md
+++ b/SecretManager/Sources/README.md
@@ -33,6 +33,7 @@ let smc = try GoogleCloudSecretManagerClient(credentials: credentialsConfigurati
 
 ```
 The order of priority for which configured projectID the SecretManagerClient will use is as follows:
+1. `$GOOGLE_PROJECT_ID` environment variable.
 1. `$PROJECT_ID` environment variable.
 2. The Service Accounts projectID (Service account configured via the credentials path in the credentials configuration).
 3. `GoogleCloudSecretManagerConfiguration`'s `project` property.
diff --git a/SecretManager/Sources/SecretManagerClient.swift b/SecretManager/Sources/SecretManagerClient.swift
index dda298c..4411e99 100644
--- a/SecretManager/Sources/SecretManagerClient.swift
+++ b/SecretManager/Sources/SecretManagerClient.swift
@@ -26,12 +26,14 @@ public final class GoogleCloudSecretManagerClient {
                                                                          eventLoop: eventLoop)
         
         /// Set the projectId to use for this client. In order of priority:
+        /// - Environment Variable (GOOGLE_PROJECT_ID) 
         /// - Environment Variable (PROJECT_ID)
         /// - Service Account's projectID
         /// - `GoogleCloudSecretManagerConfigurations` `project` property (optionally configured).
         /// - `GoogleCloudCredentialsConfiguration's` `project` property (optionally configured).
         
-        guard let projectId = ProcessInfo.processInfo.environment["PROJECT_ID"] ??
+        guard let projectId = ProcessInfo.processInfo.environment["GOOGLE_PROJECT_ID"] ??
+                              ProcessInfo.processInfo.environment["PROJECT_ID"] ??
                               (refreshableToken as? OAuthServiceAccount)?.credentials.projectId ??
                               config.project ?? credentials.project else {
             throw GoogleCloudSecretManagerError.projectIdMissing
diff --git a/Storage/Sources/README.md b/Storage/Sources/README.md
index a46e619..3aca4db 100644
--- a/Storage/Sources/README.md
+++ b/Storage/Sources/README.md
@@ -33,6 +33,7 @@ let gcs = try GoogleCloudStorageClient(credentials: credentialsConfiguration,
 
 ```
 The order of priority for which configured projectID the StorageClient will use is as follows:
+1. `$GOOGLE_PROJECT_ID` environment variable.
 1. `$PROJECT_ID` environment variable.
 2. The Service Accounts projectID (Service account configured via the credentials path in the credentials configuration).
 3. `GoogleCloudStorageConfiguration`'s `project` property.
diff --git a/Storage/Sources/StorageClient.swift b/Storage/Sources/StorageClient.swift
index b507e02..1da6366 100644
--- a/Storage/Sources/StorageClient.swift
+++ b/Storage/Sources/StorageClient.swift
@@ -36,12 +36,14 @@ public final class GoogleCloudStorageClient {
                                                                          eventLoop: eventLoop)
 
         /// Set the projectId to use for this client. In order of priority:
+        /// - Environment Variable (GOOGLE_PROJECT_ID) 
         /// - Environment Variable (PROJECT_ID)
         /// - Service Account's projectID
         /// - `GoogleCloudStorageConfigurations` `project` property (optionally configured).
         /// - `GoogleCloudCredentialsConfiguration's` `project` property (optionally configured).
         
-        guard let projectId = ProcessInfo.processInfo.environment["PROJECT_ID"] ??
+        guard let projectId = ProcessInfo.processInfo.environment["GOOGLE_PROJECT_ID"] ??
+                              ProcessInfo.processInfo.environment["PROJECT_ID"] ??
                                 (refreshableToken as? OAuthServiceAccount)?.credentials.projectId ??
                                 storageConfig.project ?? credentials.project else {
             throw GoogleCloudStorageError.projectIdMissing
diff --git a/Translation/Sources/README.md b/Translation/Sources/README.md
index ca72d8c..1ea8dfb 100644
--- a/Translation/Sources/README.md
+++ b/Translation/Sources/README.md
@@ -33,6 +33,7 @@ let gct = try GoogleCloudTranslationClient(credentials: credentialsConfiguration
 
 ```
 The order of priority for which configured projectID the TranslationClient will use is as follows:
+1. `$GOOGLE_PROJECT_ID` environment variable.
 1. `$PROJECT_ID` environment variable.
 2. The Service Accounts projectID (Service account configured via the credentials path in the credentials configuration).
 3. `GoogleCloudTranslationConfiguration`'s `project` property.
diff --git a/Translation/Sources/TranslationClient.swift b/Translation/Sources/TranslationClient.swift
index f780824..378b6ca 100644
--- a/Translation/Sources/TranslationClient.swift
+++ b/Translation/Sources/TranslationClient.swift
@@ -26,12 +26,14 @@ public final class GoogleCloudTranslationClient {
                                                                          eventLoop: eventLoop)
 
         /// Set the projectId to use for this client. In order of priority:
+        /// - Environment Variable (GOOGLE_PROJECT_ID)
         /// - Environment Variable (PROJECT_ID)
         /// - Service Account's projectID
         /// - `GoogleCloudTranslationConfigurations` `project` property (optionally configured).
         /// - `GoogleCloudCredentialsConfiguration's` `project` property (optionally configured).
 
-        guard let projectId = ProcessInfo.processInfo.environment["PROJECT_ID"] ??
+        guard let projectId = ProcessInfo.processInfo.environment["GOOGLE_PROJECT_ID"] ??
+                              ProcessInfo.processInfo.environment["PROJECT_ID"] ??
                               (refreshableToken as? OAuthServiceAccount)?.credentials.projectId ??
                               config.project ?? credentials.project else {
             throw GoogleCloudTranslationError.projectIdMissing