diff --git a/.rubocop.yml b/.rubocop.yml
index 832c31be162..e7eac17db35 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -755,19 +755,19 @@ Lint/BlockAlignment:
 # Default values in optional keyword arguments and optional ordinal arguments
 # should not refer back to the name of the argument.
 Lint/CircularArgumentReference:
-  Enabled: false
+  Enabled: true
 
 # Checks for condition placed in a confusing position relative to the keyword.
 Lint/ConditionPosition:
-  Enabled: false
+  Enabled: true
 
 # Check for debugger calls.
 Lint/Debugger:
-  Enabled: false
+  Enabled: true
 
 # Align ends corresponding to defs correctly.
 Lint/DefEndAlignment:
-  Enabled: false
+  Enabled: true
 
 # Check for deprecated class method calls.
 Lint/DeprecatedClassMethods:
@@ -783,15 +783,15 @@ Lint/DuplicatedKey:
 
 # Check for immutable argument given to each_with_object.
 Lint/EachWithObjectArgument:
-  Enabled: false
+  Enabled: true
 
 # Check for odd code arrangement in an else block.
 Lint/ElseLayout:
-  Enabled: false
+  Enabled: true
 
 # Checks for empty ensure block.
 Lint/EmptyEnsure:
-  Enabled: false
+  Enabled: true
 
 # Checks for empty string interpolation.
 Lint/EmptyInterpolation:
@@ -799,37 +799,36 @@ Lint/EmptyInterpolation:
 
 # Align ends correctly.
 Lint/EndAlignment:
-  Enabled: false
+  Enabled: true
 
 # END blocks should not be placed inside method definitions.
 Lint/EndInMethod:
-  Enabled: false
+  Enabled: true
 
 # Do not use return in an ensure block.
 Lint/EnsureReturn:
-  Enabled: false
+  Enabled: true
 
 # The use of eval represents a serious security risk.
 Lint/Eval:
-  Enabled: false
+  Enabled: true
 
 # Catches floating-point literals too large or small for Ruby to represent.
 Lint/FloatOutOfRange:
-  Enabled: false
+  Enabled: true
 
 # The number of parameters to format/sprint must match the fields.
 Lint/FormatParameterMismatch:
-  Enabled: false
+  Enabled: true
 
 # Don't suppress exception.
 Lint/HandleExceptions:
   Enabled: false
 
-# TODO: Enable ImplicitStringConcatenation Cop.
 # Checks for adjacent string literals on the same line, which could better be
 # represented as a single string literal.
 Lint/ImplicitStringConcatenation:
-  Enabled: false
+  Enabled: true
 
 # TODO: Enable IneffectiveAccessModifier Cop.
 # Checks for attempts to use `private` or `protected` to set the visibility
@@ -840,7 +839,7 @@ Lint/IneffectiveAccessModifier:
 # Checks for invalid character literals with a non-escaped whitespace
 # character.
 Lint/InvalidCharacterLiteral:
-  Enabled: false
+  Enabled: true
 
 # Checks of literals used in conditions.
 Lint/LiteralInCondition:
@@ -848,7 +847,7 @@ Lint/LiteralInCondition:
 
 # Checks for literals used in interpolation.
 Lint/LiteralInInterpolation:
-  Enabled: false
+  Enabled: true
 
 # Use Kernel#loop with break rather than begin/end/until or begin/end/while
 # for post-loop tests.
@@ -857,11 +856,11 @@ Lint/Loop:
 
 # Do not use nested method definitions.
 Lint/NestedMethodDefinition:
-  Enabled: false
+  Enabled: true
 
 # Do not omit the accumulator when calling `next` in a `reduce`/`inject` block.
 Lint/NextWithoutAccumulator:
-  Enabled: false
+  Enabled: true
 
 # Checks for method calls with a space before the opening parenthesis.
 Lint/ParenthesesAsGroupedExpression:
@@ -870,11 +869,11 @@ Lint/ParenthesesAsGroupedExpression:
 # Checks for `rand(1)` calls. Such calls always return `0` and most likely
 # a mistake.
 Lint/RandOne:
-  Enabled: false
+  Enabled: true
 
 # Use parentheses in the method call to avoid confusion about precedence.
 Lint/RequireParentheses:
-  Enabled: false
+  Enabled: true
 
 # Avoid rescuing the Exception class.
 Lint/RescueException:
@@ -909,7 +908,7 @@ Lint/UnusedMethodArgument:
 
 # Unreachable code.
 Lint/UnreachableCode:
-  Enabled: false
+  Enabled: true
 
 # Checks for useless access modifiers.
 Lint/UselessAccessModifier:
@@ -921,19 +920,19 @@ Lint/UselessAssignment:
 
 # Checks for comparison of something with itself.
 Lint/UselessComparison:
-  Enabled: false
+  Enabled: true
 
 # Checks for useless `else` in `begin..end` without `rescue`.
 Lint/UselessElseWithoutRescue:
-  Enabled: false
+  Enabled: true
 
 # Checks for useless setter call to a local variable.
 Lint/UselessSetterCall:
-  Enabled: false
+  Enabled: true
 
 # Possible use of operator/literal/variable in void context.
 Lint/Void:
-  Enabled: false
+  Enabled: true
 
 
 ##################### Performance ############################
@@ -942,11 +941,10 @@ Lint/Void:
 Performance/Casecmp:
   Enabled: true
 
-# TODO: Enable DoubleStartEndWith Cop.
 # Use `str.{start,end}_with?(x, ..., y, ...)` instead of
 # `str.{start,end}_with?(x, ...) || str.{start,end}_with?(y, ...)`.
 Performance/DoubleStartEndWith:
-  Enabled: false
+  Enabled: true
 
 # TODO: Enable EndWith Cop.
 # Use `end_with?` instead of a regex match anchored to the end of a string.
@@ -980,10 +978,9 @@ Performance/RedundantMerge:
   MaxKeyValuePairs: 2
   Enabled: false
 
-# TODO: Enable RedundantSortBy Cop.
 # Use `sort` instead of `sort_by { |x| x }`.
 Performance/RedundantSortBy:
-  Enabled: false
+  Enabled: true
 
 # Use `start_with?` instead of a regex match anchored to the beginning of a
 # string.
@@ -1024,11 +1021,11 @@ Rails/Delegate:
 
 # Prefer `find_by` over `where.first`.
 Rails/FindBy:
-  Enabled: false
+  Enabled: true
 
 # Prefer `all.find_each` over `all.find`.
 Rails/FindEach:
-  Enabled: false
+  Enabled: true
 
 # Prefer has_many :through to has_and_belongs_to_many.
 Rails/HasAndBelongsToMany:
@@ -1040,7 +1037,7 @@ Rails/Output:
 
 # Checks for incorrect grammar when using methods like `3.day.ago`.
 Rails/PluralizationGrammar:
-  Enabled: false
+  Enabled: true
 
 # Checks for `read_attribute(:attr)` and `write_attribute(:attr, val)`.
 Rails/ReadWriteAttribute:
@@ -1048,7 +1045,7 @@ Rails/ReadWriteAttribute:
 
 # Checks the arguments of ActiveRecord scopes.
 Rails/ScopeArgs:
-  Enabled: false
+  Enabled: true
 
 # Checks the correct usage of time zone aware methods.
 # http://danilenko.org/2012/7/6/rails_timezones