diff --git a/app/models/dro.rb b/app/models/dro.rb
index d5deb89f5..53c563d2b 100644
--- a/app/models/dro.rb
+++ b/app/models/dro.rb
@@ -5,6 +5,11 @@ class Dro < RepositoryRecord
   validates :content_type, :access, :administrative, :description,
             :identification, :structural, presence: true
 
+  scope :has_admin_policy, ->(admin_policy_druid) { where("administrative ->> 'hasAdminPolicy' = '#{admin_policy_druid}'").select(:external_identifier).order(:external_identifier) }
+  scope :in_virtual_objects, ->(member_druid) { where("structural #> '{hasMemberOrders,0}' -> 'members' ? :druid", druid: member_druid) }
+  scope :members_of_collection, ->(collection_druid) { where("structural -> 'isMemberOf' ? :druid", druid: collection_druid).select(:external_identifier, :version, :content_type) }
+  scope :embargoed_and_releaseable, -> { where("(access -> 'embargo' ->> 'releaseDate')::timestamp <= ?", Time.zone.now).select(:external_identifier) }
+
   def self.find_by_source_id(source_id)
     find_by("identification->>'sourceId' = ?", source_id)
   end
diff --git a/app/reports/apo_catkey.rb b/app/reports/apo_catkey.rb
index 4255656a8..d0affa8e6 100644
--- a/app/reports/apo_catkey.rb
+++ b/app/reports/apo_catkey.rb
@@ -2,7 +2,7 @@
 
 require 'csv'
 
-# Find items that are goverened by the provided APO and then return all catkeys and refresh status.
+# Find items that are governed by the provided APO and then return all catkeys and refresh status.
 #  https://github.com/sul-dlss/dor-services-app/issues/4373
 # Invoke via:
 # bin/rails r -e production "ApoCatkey.report('druid:bx911tp9024')"
@@ -12,17 +12,7 @@ def self.report(apo_druid)
 
     CSV.open(output_file, 'w') do |csv|
       csv << %w[druid catkey refresh]
-      query = "is_governed_by_ssim:\"info:fedora/#{apo_druid}\"&objectType_ssim:\"item\""
-      druids = []
-      # borrowed from bin/generate-druid-list
-      loop do
-        results = SolrService.query('*:*', fl: 'id', rows: 10000, fq: query, start: druids.length, sort: 'id asc')
-        break if results.empty?
-
-        results.each { |r| druids << r['id'] }
-        sleep(0.5)
-      end
-
+      druids = Dro.has_admin_policy(apo_druid).map(&:external_identifier)
       num_dros = druids.size
       puts "Found #{num_dros} objects that are governed by APO #{apo_druid}"
       druids.each_with_index do |druid, i|
diff --git a/app/services/delete_service.rb b/app/services/delete_service.rb
index 8cc955603..031798b52 100644
--- a/app/services/delete_service.rb
+++ b/app/services/delete_service.rb
@@ -4,7 +4,6 @@
 class DeleteService
   # Tries to remove any existence of the object in our systems
   #   Does the following:
-  #   - Removes item from Fedora/Solr
   #   - Removes content from dor workspace
   #   - Removes content from assembly workspace
   #   - Removes content from sdr export area
diff --git a/app/services/embargo_release_service.rb b/app/services/embargo_release_service.rb
index d819b43d3..b2baa2ca8 100644
--- a/app/services/embargo_release_service.rb
+++ b/app/services/embargo_release_service.rb
@@ -1,27 +1,23 @@
 # frozen_string_literal: true
 
 # Finds objects where the embargo release date has passed for embargoed items
-# Builds list of candidate objects by doing a Solr query
+# Builds list of candidate objects by querying the database
 #
 # Should run once a day from cron
 class EmbargoReleaseService
-  RELEASEABLE_NOW_QUERY = 'embargo_status_ssim:"embargoed" AND embargo_release_dtsim:[* TO NOW]'
-
   def self.release_all
     # Find objects to process
-    Rails.logger.info("***** Querying solr: #{RELEASEABLE_NOW_QUERY}")
-    solr = SolrService.get(RELEASEABLE_NOW_QUERY, 'rows' => '5000', 'fl' => 'id')
+    embargoed_items_to_release = Dro.embargoed_and_releaseable
 
-    num_found = solr['response']['numFound'].to_i
-    if num_found.zero?
+    if embargoed_items_to_release.none?
       Rails.logger.info('No objects to process')
       return
     end
-    Rails.logger.info("Found #{num_found} objects")
+    Rails.logger.info("Found #{embargoed_items_to_release.count} objects")
 
     count = 0
-    solr['response']['docs'].each do |doc|
-      release(doc['id'])
+    embargoed_items_to_release.each do |item|
+      release(item.external_identifier)
       count += 1
     end
 
diff --git a/app/services/member_service.rb b/app/services/member_service.rb
index 95c13348c..591f2cdb9 100644
--- a/app/services/member_service.rb
+++ b/app/services/member_service.rb
@@ -1,19 +1,37 @@
 # frozen_string_literal: true
 
-# Finds the members of a collection by using Solr
+# Finds the members of a collection
 class MemberService
   # @param [String] druid the identifier of the collection
   # @param [Boolean] only_published when true, restrict to only published items
   # @param [Boolean] exclude_opened when true, exclude opened items
   # @return [Array<Hash<String,String>>] the members of this collection
   def self.for(druid, only_published: false, exclude_opened: false)
-    query = "is_member_of_collection_ssim:\"info:fedora/#{druid}\""
-    query += ' published_dttsim:[* TO *]' if only_published
-    query += ' -processing_status_text_ssi:Opened' if exclude_opened
-    args = {
-      fl: 'id,objectType_ssim',
-      rows: 100_000_000
-    }
-    SolrService.query query, args
+    Dro
+      .members_of_collection(druid)
+      .then { |members| reject_opened_members(members, exclude_opened) }
+      .then { |members| select_published_members(members, only_published) }
+      .map do |member|
+      {
+        'id' => member.external_identifier,
+        'objectType' => member.content_type == Cocina::Models::ObjectType.agreement ? 'agreement' : 'item'
+      }
+    end
+  end
+
+  def self.reject_opened_members(members, exclude_opened)
+    return members unless exclude_opened
+
+    members.reject do |member|
+      WorkflowClientFactory.build.status(druid: member.external_identifier, version: member.version).display_simplified == 'Opened'
+    end
+  end
+
+  def self.select_published_members(members, only_published)
+    return members unless only_published
+
+    members.select do |member|
+      WorkflowClientFactory.build.lifecycle(druid: member.external_identifier, milestone_name: 'published', version: member.version).present?
+    end
   end
 end
diff --git a/app/services/publish/public_desc_metadata_service.rb b/app/services/publish/public_desc_metadata_service.rb
index 92774671c..5b8fd80d4 100644
--- a/app/services/publish/public_desc_metadata_service.rb
+++ b/app/services/publish/public_desc_metadata_service.rb
@@ -57,7 +57,7 @@ def add_doi
     # expand constituent relations into relatedItem references -- see JUMBO-18
     # @return [Void]
     def add_constituent_relations!
-      VirtualObject.for(druid: cocina_object.externalIdentifier).each do |solr_doc|
+      VirtualObject.for(druid: cocina_object.externalIdentifier).each do |virtual_object_hash|
         # create the MODS relation
         relatedItem = doc.create_element('relatedItem', xmlns: MODS_NS)
         relatedItem['type'] = 'host'
@@ -66,14 +66,14 @@ def add_constituent_relations!
         # load the title from the virtual object's DC.title
         titleInfo = doc.create_element('titleInfo', xmlns: MODS_NS)
         title = doc.create_element('title', xmlns: MODS_NS)
-        title.content = solr_doc.fetch(:title)
+        title.content = virtual_object_hash.fetch(:title)
         titleInfo << title
         relatedItem << titleInfo
 
         # point to the PURL for the virtual object
         location = doc.create_element('location', xmlns: MODS_NS)
         url = doc.create_element('url', xmlns: MODS_NS)
-        url.content = purl_url(solr_doc.fetch(:id))
+        url.content = purl_url(virtual_object_hash.fetch(:id))
         location << url
         relatedItem << location
 
diff --git a/app/services/published_relationships_filter.rb b/app/services/published_relationships_filter.rb
index c1aa88892..9a43724e8 100644
--- a/app/services/published_relationships_filter.rb
+++ b/app/services/published_relationships_filter.rb
@@ -36,8 +36,8 @@ def collections
   def virtual_objects
     return unless cocina_object.dro?
 
-    VirtualObject.for(druid: cocina_object.externalIdentifier).map do |solr_doc|
-      "<fedora:isConstituentOf rdf:resource=\"info:fedora/#{solr_doc.fetch(:id)}\"/>"
+    VirtualObject.for(druid: cocina_object.externalIdentifier).map do |virtual_object_hash|
+      "<fedora:isConstituentOf rdf:resource=\"info:fedora/#{virtual_object_hash.fetch(:id)}\"/>"
     end.join(INDENT)
   end
 end
diff --git a/app/services/solr_service.rb b/app/services/solr_service.rb
deleted file mode 100644
index 7ac194855..000000000
--- a/app/services/solr_service.rb
+++ /dev/null
@@ -1,38 +0,0 @@
-# frozen_string_literal: true
-
-# Functions for querying solr
-class SolrService
-  include Singleton
-
-  def options
-    { timeout: Settings.solr.timeout, url: Settings.solr.url }
-  end
-
-  def conn
-    @conn ||= RSolr.connect options
-  end
-
-  class << self
-    delegate :conn, to: :instance
-
-    def select_path
-      Settings.solr.select_path
-    end
-
-    # @param [Hash] options
-    def get(query, args = {})
-      args = args.merge(q: query, wt: :json)
-      conn.get(select_path, params: args)
-    end
-
-    def query(query, args = {})
-      unless args.key?(:rows)
-        Rails.logger.warn "Calling SolrService.get without passing an explicit value for ':rows' is not recommended. " \
-                          "You will end up with Solr's default (usually set to 10)\nCalled by #{caller(1..1).first}"
-      end
-      get(query, args).fetch('response').fetch('docs')
-    end
-
-    delegate :add, :commit, to: :conn
-  end
-end
diff --git a/app/services/virtual_object.rb b/app/services/virtual_object.rb
index 79ccf3269..d8ccc741b 100644
--- a/app/services/virtual_object.rb
+++ b/app/services/virtual_object.rb
@@ -6,10 +6,11 @@ class VirtualObject
   # @param [String] druid
   # @return [Array<Hash>] a list of results with ids and titles
   def self.for(druid:)
-    query = "has_constituents_ssim:#{druid.sub(':', '\:')}"
-    response = SolrService.get(query, { fl: 'id sw_display_title_tesim' })
-    response.fetch('response').fetch('docs').map do |row|
-      { id: row.fetch('id'), title: row.fetch('sw_display_title_tesim').first }
+    Dro.in_virtual_objects(druid).map do |dro|
+      {
+        id: dro.external_identifier,
+        title: Cocina::Models::Builders::TitleBuilder.build(dro.to_cocina.description.title)
+      }
     end
   end
 end
diff --git a/bin/clean-druid-list b/bin/clean-druid-list
index 5e2cf91cd..ae811ff20 100755
--- a/bin/clean-druid-list
+++ b/bin/clean-druid-list
@@ -23,7 +23,9 @@ count = 0
 File.open(options[:output], 'w') do |file|
   druids.each_with_index do |druid, index|
     puts "Finding #{druid} (#{index + 1})"
-    next if SolrService.query('*:*', fl: 'id', rows: 1, fq: "id:\"#{druid}\"").empty?
+    next unless AdminPolicy.exists?(external_identifier: druid) ||
+                Collection.exists?(external_identifier: druid) ||
+                Dro.exists?(external_identifier: druid)
 
     file.write("#{druid}\n")
     count += 1
diff --git a/bin/generate-druid-list b/bin/generate-druid-list
index bfa89ae80..4b1bf5b48 100755
--- a/bin/generate-druid-list
+++ b/bin/generate-druid-list
@@ -4,6 +4,8 @@
 require_relative '../config/environment'
 require 'optparse'
 
+# TODO: Figure out if we still want this or not, given how tightly coupled this functionality is to Solr
+
 options = { output: 'druids.txt', quiet: false }
 parser = OptionParser.new do |option_parser|
   option_parser.banner = 'Usage: bin/generate-druid-list \'<QUERY, e.g., project_tag_ssim:"Naxos : born digital audio">\' [options]'
diff --git a/lib/tasks/missing_druids.rake b/lib/tasks/missing_druids.rake
index 26cb87a5d..c1a18e18c 100644
--- a/lib/tasks/missing_druids.rake
+++ b/lib/tasks/missing_druids.rake
@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
+# TODO: Figure out if we still want this or not, given how tightly coupled this functionality is to Solr
+
 namespace :missing_druids do
   desc 'Find unindexed druids'
   task unindexed_objects: :environment do