diff --git a/app/scripts/contentscript.js b/app/scripts/contentscript.js
index 7e55faec4..116cad02d 100644
--- a/app/scripts/contentscript.js
+++ b/app/scripts/contentscript.js
@@ -4,6 +4,7 @@ import LocalMessageDuplexStream from 'post-message-stream'
 import ObjectMultiplex from 'obj-multiplex'
 import extension from 'extensionizer'
 import PortStream from 'extension-port-stream'
+import { obj as createThoughStream } from 'through2'
 
 // These require calls need to use require to be statically recognized by browserify
 const fs = require('fs')
@@ -20,6 +21,12 @@ const CONTENT_SCRIPT = 'metamask-contentscript'
 const INPAGE = 'metamask-inpage'
 const PROVIDER = 'metamask-provider'
 
+// TODO:LegacyProvider: Delete
+const LEGACY_CONTENT_SCRIPT = 'contentscript'
+const LEGACY_INPAGE = 'inpage'
+const LEGACY_PROVIDER = 'provider'
+const LEGACY_PUBLIC_CONFIG = 'publicConfig'
+
 if (shouldInjectProvider()) {
   injectScript(inpageBundle)
   setupStreams()
@@ -63,6 +70,7 @@ async function setupStreams() {
   pageMux.setMaxListeners(25)
   const extensionMux = new ObjectMultiplex()
   extensionMux.setMaxListeners(25)
+  extensionMux.ignoreStream(LEGACY_PUBLIC_CONFIG) // TODO:LegacyProvider: Delete
 
   pump(pageMux, pageStream, pageMux, (err) =>
     logStreamDisconnectWarning('MetaMask Inpage Multiplex', err),
@@ -78,6 +86,44 @@ async function setupStreams() {
   // connect "phishing" channel to warning system
   const phishingStream = extensionMux.createStream('phishing')
   phishingStream.once('data', redirectToPhishingWarning)
+
+  // TODO:LegacyProvider: Delete
+  // handle legacy provider
+  const legacyPageStream = new LocalMessageDuplexStream({
+    name: LEGACY_CONTENT_SCRIPT,
+    target: LEGACY_INPAGE,
+  })
+
+  const legacyPageMux = new ObjectMultiplex()
+  legacyPageMux.setMaxListeners(25)
+  const legacyExtensionMux = new ObjectMultiplex()
+  legacyExtensionMux.setMaxListeners(25)
+
+  pump(legacyPageMux, legacyPageStream, legacyPageMux, (err) =>
+    logStreamDisconnectWarning('MetaMask Legacy Inpage Multiplex', err),
+  )
+  pump(
+    legacyExtensionMux,
+    extensionStream,
+    getNotificationTransformStream(),
+    legacyExtensionMux,
+    (err) => {
+      logStreamDisconnectWarning('MetaMask Background Legacy Multiplex', err)
+      notifyInpageOfStreamFailure()
+    },
+  )
+
+  forwardNamedTrafficBetweenMuxes(
+    LEGACY_PROVIDER,
+    PROVIDER,
+    legacyPageMux,
+    legacyExtensionMux,
+  )
+  forwardTrafficBetweenMuxes(
+    LEGACY_PUBLIC_CONFIG,
+    legacyPageMux,
+    legacyExtensionMux,
+  )
 }
 
 function forwardTrafficBetweenMuxes(channelName, muxA, muxB) {
@@ -91,6 +137,37 @@ function forwardTrafficBetweenMuxes(channelName, muxA, muxB) {
   )
 }
 
+// TODO:LegacyProvider: Delete
+function forwardNamedTrafficBetweenMuxes(
+  channelAName,
+  channelBName,
+  muxA,
+  muxB,
+) {
+  const channelA = muxA.createStream(channelAName)
+  const channelB = muxB.createStream(channelBName)
+  pump(channelA, channelB, channelA, (error) =>
+    console.debug(
+      `MetaMask: Muxed traffic between channels "${channelAName}" and "${channelBName}" failed.`,
+      error,
+    ),
+  )
+}
+
+// TODO:LegacyProvider: Delete
+function getNotificationTransformStream() {
+  return createThoughStream((chunk, _, cb) => {
+    if (chunk?.name === PROVIDER) {
+      if (chunk.data?.method === 'metamask_accountsChanged') {
+        chunk.data.method = 'wallet_accountsChanged'
+        chunk.data.result = chunk.data.params
+        delete chunk.data.params
+      }
+    }
+    cb(null, chunk)
+  })
+}
+
 /**
  * Error handler for page to extension stream disconnections
  *
diff --git a/app/scripts/metamask-controller.js b/app/scripts/metamask-controller.js
index 0608ac2b8..2e76464aa 100644
--- a/app/scripts/metamask-controller.js
+++ b/app/scripts/metamask-controller.js
@@ -1,6 +1,8 @@
 import EventEmitter from 'events'
 import pump from 'pump'
 import Dnode from 'dnode'
+import { ObservableStore } from '@metamask/obs-store'
+import { storeAsStream } from '@metamask/obs-store/dist/asStream'
 import { JsonRpcEngine } from 'json-rpc-engine'
 import { debounce } from 'lodash'
 import createEngineStream from 'json-rpc-middleware-stream/engineStream'
@@ -413,6 +415,9 @@ export default class MetamaskController extends EventEmitter {
     ) {
       this.submitPassword(password)
     }
+
+    // TODO:LegacyProvider: Delete
+    this.publicConfigStore = this.createPublicConfigStore()
   }
 
   /**
@@ -459,6 +464,38 @@ export default class MetamaskController extends EventEmitter {
     return providerProxy
   }
 
+  /**
+   * TODO:LegacyProvider: Delete
+   * Constructor helper: initialize a public config store.
+   * This store is used to make some config info available to Dapps synchronously.
+   */
+  createPublicConfigStore() {
+    // subset of state for metamask inpage provider
+    const publicConfigStore = new ObservableStore()
+    const { networkController } = this
+
+    // setup memStore subscription hooks
+    this.on('update', updatePublicConfigStore)
+    updatePublicConfigStore(this.getState())
+
+    function updatePublicConfigStore(memState) {
+      const chainId = networkController.getCurrentChainId()
+      if (memState.network !== 'loading') {
+        publicConfigStore.putState(selectPublicState(chainId, memState))
+      }
+    }
+
+    function selectPublicState(chainId, { isUnlocked, network }) {
+      return {
+        isUnlocked,
+        chainId,
+        networkVersion: network,
+      }
+    }
+
+    return publicConfigStore
+  }
+
   /**
    * Gets relevant state for the provider of an external origin.
    *
@@ -1831,6 +1868,10 @@ export default class MetamaskController extends EventEmitter {
 
     // messages between inpage and background
     this.setupProviderConnection(mux.createStream('metamask-provider'), sender)
+
+    // TODO:LegacyProvider: Delete
+    // legacy streams
+    this.setupPublicConfig(mux.createStream('publicConfig'))
   }
 
   /**
@@ -2016,6 +2057,28 @@ export default class MetamaskController extends EventEmitter {
     return engine
   }
 
+  /**
+   * TODO:LegacyProvider: Delete
+   * A method for providing our public config info over a stream.
+   * This includes info we like to be synchronous if possible, like
+   * the current selected account, and network ID.
+   *
+   * Since synchronous methods have been deprecated in web3,
+   * this is a good candidate for deprecation.
+   *
+   * @param {*} outStream - The stream to provide public config over.
+   */
+  setupPublicConfig(outStream) {
+    const configStream = storeAsStream(this.publicConfigStore)
+
+    pump(configStream, outStream, (err) => {
+      configStream.destroy()
+      if (err) {
+        log.error(err)
+      }
+    })
+  }
+
   /**
    * Adds a reference to a connection by origin. Ignores the 'metamask' origin.
    * Caller must ensure that the returned id is stored such that the reference