diff --git a/src/modules/orbitdb/indexes/abstract.js b/src/modules/orbitdb/indexes/abstract.js
index cb09fc3..bfc0ad4 100644
--- a/src/modules/orbitdb/indexes/abstract.js
+++ b/src/modules/orbitdb/indexes/abstract.js
@@ -164,6 +164,10 @@ class ChluAbstractIndex {
         return await this._getReviewsWrittenByDID(didId)
     }
 
+    async getReputationScore(didId) {
+        return await this._getReputationScore(didId)
+    }
+
     async _getReviewsAboutDID() {
         notImplemented();
     }
@@ -172,6 +176,10 @@ class ChluAbstractIndex {
         notImplemented();
     }
 
+    async _getReputationScore() {
+        notImplemented()
+    }
+
 }
 
 function notImplemented() {
diff --git a/src/modules/orbitdb/indexes/inmemory.js b/src/modules/orbitdb/indexes/inmemory.js
index 3f9db04..ea26911 100644
--- a/src/modules/orbitdb/indexes/inmemory.js
+++ b/src/modules/orbitdb/indexes/inmemory.js
@@ -133,6 +133,11 @@ class ChluInMemoryIndex extends ChluAbstractIndex {
             .map(multihash => ({ multihash }))
     }
 
+    _getReputationScore() {
+        // The InMemory Index cannot do this.
+        return null
+    }
+
 }
 
 function slice(array, offset, limit) {
diff --git a/src/modules/orbitdb/indexes/sql.js b/src/modules/orbitdb/indexes/sql.js
index 700d68b..a819fe5 100644
--- a/src/modules/orbitdb/indexes/sql.js
+++ b/src/modules/orbitdb/indexes/sql.js
@@ -289,6 +289,35 @@ class ChluSQLIndex extends ChluAbstractIndex {
         return formatReviewRecords(list)
     }
 
+    async _getReputationScore(didId) {
+        const result = await this.ReviewRecord.findAll({
+            attributes: [
+                [this.sequelize.fn('AVERAGE', this.sequelize.col('data.rating_details.value')), 'rating_average'],
+                [this.sequelize.fn('COUNT'), 'rating_count'],
+            ],
+            where: {
+                // Only take out reviews about the didId
+                [Sequelize.Op.or]: [
+                    { 'data.popr.vendor_did': didId },
+                    { 'data.subject.did': didId },
+                ],
+                // that also have a rating between 1 and 5 included
+                'data.rating_details.min': 1,
+                'data.rating_details.max': 5,
+                'data.rating_details.value': {
+                    [Sequelize.Op.gte]: 1,
+                    [Sequelize.Op.lte]: 5
+                },
+                // don't consider records not about the latest version of a review
+                'latestVersionData': null
+            }
+        })
+        return {
+            rating_average: get(result[0], 'rating_average', null),
+            rating_count: get(result[0], 'rating_count', 0),
+        }
+    }
+
 }
 
 function formatReviewRecords(list) {
diff --git a/tests/OrbitDB.test.js b/tests/OrbitDB.test.js
index e2bfeb1..34c56e7 100644
--- a/tests/OrbitDB.test.js
+++ b/tests/OrbitDB.test.js
@@ -12,6 +12,7 @@ const ChluInMemoryIndex = require('../src/modules/orbitdb/indexes/inmemory');
 const ChluAbstractIndex = require('../src/modules/orbitdb/indexes/abstract');
 const { genMultihash } = require('./utils/ipfs');
 const { getFakeReviewRecord, makeResolved } = require('./utils/protobuf');
+const { cloneDeep } = require('lodash')
 
 async function applyOperation(idx, op) {
     return await idx.updateIndex({
@@ -40,7 +41,7 @@ describe('OrbitDB Module', () => {
             directory
         });
         chluIpfs.reviewRecords.readReviewRecord = sinon.stub()
-            .callsFake(async multihash => Object.assign({ multihash }, makeResolved(await getFakeReviewRecord()), reviewOverride || {}))
+            .callsFake(async multihash => Object.assign({ multihash }, cloneDeep(makeResolved(await getFakeReviewRecord()), reviewOverride || {})))
         chluIpfs.didIpfsHelper.readPublicDIDDocument = sinon.stub()
             .callsFake(async () => Object.assign({
                 id: 'did:chlu:random'
@@ -207,12 +208,10 @@ describe('OrbitDB Module', () => {
                     reviewOverride = { popr: { vendor_did: didId } }
                     await applyOperation(idx, {
                         op: ChluInMemoryIndex.operations.ADD_REVIEW_RECORD,
-                        didId, // Retrocompatibility
                         multihash: genMultihash(1)
                     })
                     await applyOperation(idx, {
                         op: ChluInMemoryIndex.operations.ADD_REVIEW_RECORD,
-                        subjectDidId: didId,
                         multihash: genMultihash(2)
                     })
                     expect((await idx.getReviewsAboutDID(didId)).map(x => x.multihash)).to.deep.equal([
@@ -222,6 +221,37 @@ describe('OrbitDB Module', () => {
                     expect(await idx.getReviewsWrittenByDID(didId)).to.deep.equal([])
                 })
 
+                function getRating(x) { return { min: 1, max: 5, value: x } }
+                const skipForInMemory = item.name === 'InMemory' ? it.skip : it.only
+
+                skipForInMemory('computes reputation score about subject DID', async () => {
+                    const didId = 'did:chlu:abc'
+                    reviewOverride = { popr: { vendor_did: didId }, rating_details: getRating(1) }
+                    await applyOperation(idx, {
+                        op: ChluInMemoryIndex.operations.ADD_REVIEW_RECORD,
+                        subjectDidId: didId,
+                        multihash: genMultihash(1)
+                    })
+                    reviewOverride = { popr: { vendor_did: didId }, rating_details: getRating(1) }
+                    await applyOperation(idx, {
+                        op: ChluInMemoryIndex.operations.ADD_REVIEW_RECORD,
+                        subjectDidId: didId,
+                        multihash: genMultihash(2)
+                    })
+                    reviewOverride = { subject: { did: didId }, previous_version_multihash: genMultihash(2), history: [
+                        { multihash: genMultihash(2) }
+                    ], rating_details: getRating(5) }
+                    await applyOperation(idx, {
+                        op: ChluInMemoryIndex.operations.ADD_REVIEW_RECORD,
+                        subjectDidId: didId,
+                        multihash: genMultihash(3)
+                    })
+                    expect(await idx.getReputationScore(didId)).to.deep.equal({
+                        average_score: 3,
+                        count: 2
+                    })
+                })
+
                 it('returns reviews written by author DID', async () => {
                     const didId = 'did:chlu:abc'
                     reviewOverride = { customer_signature: { creator: didId } }