
584 N.W.2d 654 (1998)
230 Mich. App. 723
In the Matter of Lawrence NEAL and Richard Neal, Legally Incapacitated Persons.
Virginia NEAL, Petitioner-Appellee, and
Warren D. Sundstrand, Guardian Ad Litem, and Mary C. Combs and Harold Neal, Appellees,
v.
Richard NEAL, Respondent-Appellant, and
Lawrence Neal, Respondent.
Docket No. 199884.
Court of Appeals of Michigan.
Submitted February 10, 1998, at Grand Rapids.
Decided July 24, 1998, at 9:05 a.m.
Released for Publication October 7, 1998.
*655 Schuitmaker, Clarke & Cooper, P.C. (by Harold Schuitmaker), Paw Paw, for Petitioner-Appellee.
David Michael Stokes, Livonia, for Respondent-Appellant.
Before RICHARD ALLEN GRIFFIN, P.J., and HOLBROOK, and NEFF, JJ.
NEFF, Judge.
Respondent Richard Neal appeals by leave granted the circuit court decision that affirmed the probate court's appointment of limited coguardians and coconservators for him pursuant to article 4 of the Revised Probate Code, M.C.L. § 700.401 et seq.; M.S.A. § 27.5401 et seq.[1] We reverse and remand.

I
Richard and his twin brother Lawrence were born January 1, 1949. Because of a medical complication arising from the incompatibility of blood between the boys' parents, both Lawrence and Richard became mentally impaired and were retarded in their development. Richard's family made a concerted effort to ensure that both boys received an education and upbringing that would prepare them to be as independent as possible. For over twenty years, both Lawrence and Richard maintained steady employment. However, for most of their lives their financial and other living arrangements have been handled by their parents and other immediate family members in what both parties describe as a "de facto guardianship."
Following the death of their father in 1992, both brothers sought more independence from their family. They contacted the Van Buren County Community Mental Health agency for assistance and developed new friendships through that agency's "circle of friends" support group program. Richard quit his full-time job in South Haven to move into the Bangor home of his friend Marilyn Schneider, whom he intends to marry. Although Richard obtained a part-time job bagging groceries, his job change resulted in a loss of health insurance benefits.
In October 1995, Richard's mother, Virginia Neal, petitioned the probate court for appointment as guardian and conservator of both Lawrence and Richard, as legally incapacitated persons, pursuant to the Revised Probate Code. Lawrence and Richard filed a motion for summary disposition, arguing that because they were developmentally disabled, any guardianship proceedings should proceed under chapter 6 of the Mental Health Code. The probate court denied the motion and issued a lengthy and detailed opinion and order appointing Lawrence and Richard's mother, brother, and sister as limited coguardians and coconservators for Lawrence and Richard pursuant to the Revised Probate Code.
The circuit court affirmed the decision of the probate court, finding that there was no error in the trial court's characterization of Lawrence and Richard as legally incapacitated and that a determination whether they were also developmentally disabled was unnecessary and merely exalted form over function. Richard now appeals by leave granted.

II
Richard first argues that the probate court erred in appointing a guardian under the procedures contained in article 4 of the Revised Probate Code, M.C.L. § 700.401 et seq.; M.S.A. § 27.5401 et seq. Richard insists that he is, and continues to be, a person with a developmental disability; therefore, any *656 guardianship proceedings should have been conducted according to chapter 6 of the Mental Health Code, M.C.L. § 330.1600 et seq.; M.S.A. § 14.800(600) et seq. We agree.

A
The Revised Probate Code and the Mental Health Code each provide mechanisms through which an interested person can petition the probate court for the appointment of a guardian and which mirror each other to a significant degree. Importantly however, the Mental Health Code provides that, except in the case of minors, a guardian for a developmentally disabled person may be made pursuant only to chapter 6 of the Mental Health Code. M.C.L. § 330.1604(2); M.S.A. § 14.800(604)(2). Accordingly, if Richard was a developmentally disabled person at the time of the guardianship proceedings, then only chapter 6 of the Mental Health Code could be used to appoint a guardian for him, regardless of whether Richard also satisfied the definition of a legally incapacitated person as defined in the Revised Probate Code.[2]
At all times relevant to this appeal, the Mental Health Code defined "developmental disability" as "an impairment of general intellectual functioning or adaptive behavior" that "has continued since its origination or can be expected to continue indefinitely" and that "constitutes a substantial burden to the impaired person's ability to perform normally in society" and that "is attributable to ... [m]ental retardation, cerebral palsy, epilepsy, or autism," or to any other condition producing a similar impairment or to dyslexia resulting from any of the above. M.C.L. § 330.1600(e); M.S.A. § 14.800(600)(e).[3] We have carefully reviewed the record and find that, without question, Richard falls within this definition.[4] Accordingly, because Richard is a developmentally disabled person, the probate court erred in conducting the guardianship proceedings pursuant to article 4 of the Probate Code.

B
The coguardians argue that any error in the probate court's use of the wrong statutory procedure was harmless. We disagree.
The Mental Health Code provides safeguards to protect the substantive rights *657 of the developmentally disabled. Michigan Ass'n for Retarded Citizens v. Wayne Co. Probate Judge, 79 Mich.App. 487, 492, 261 N.W.2d 60 (1977). Our Supreme Court has stated that the powers of the probate court to appoint a guardian are purely statutory and that the requirements of the applicable statutes must be strictly observed. Stevens v. Stevens, 266 Mich. 446, 449, 254 N.W. 162 (1934). Here, the mandate of M.C.L. § 330.1604(2); M.S.A. § 14.800(604)(2) is clear and unambiguous: "An appointment of a guardian for a developmentally disabled person shall be made only pursuant to [the Mental Health Code]." The word "shall" indicates a mandatory, nondiscretionary provision. In re Hall-Smith, 222 Mich.App. 470, 472, 564 N.W.2d 156 (1997). Consequently, the appointment of a guardian for a developmentally disabled person under the Revised Probate Code would directly contradict the Legislature's clear mandate that such proceedings must be conducted pursuant to the Mental Health Code.
Appellees' argument, that the facts of this case would support the establishment of a guardianship under either code ignores the Legislature's decision to afford certain safeguards to the developmentally disabled not afforded to persons alleged to be legally incapacitated.[5] These safeguards would be nullified if a party petitioning for the appointment of a guardian for a developmentally disabled person were allowed to proceed under the Revised Probate Code.
We conclude that only chapter 6 of the Mental Health Code may be used to appoint a guardian for a developmentally disabled adult, regardless of whether that person also satisfies the definition of a legally incapacitated person as defined in the Revised Probate Code. The probate court erred in not following this clear statutory mandate, and the circuit court erred in affirming the decision of the probate court. By conducting the guardianship proceedings under the Revised Probate Code, the probate court denied Richard the protections that the Legislature has specifically afforded to the developmentally disabled under the Mental Health Code. *658 Because this error is not harmless, we reverse the judgment of the circuit court and remand this case with instructions that the probate court dissolve the guardianships and conservatorships. Petitioner is free to file a new petition for guardianship pursuant to the Mental Health Code.

III
Because of our determination that reversal is required, we need not address Richard's remaining issues on appeal.
Reversed and remanded. We do not retain jurisdiction.
NOTES
[1]  Respondent Lawrence Neal, for whom coguardians and coconservators were also appointed, has withdrawn his appeal from our consideration.
[2]  Section 8(2) of the Revised Probate Code, M.C.L. § 700.8(2); M.S.A. § 27.5008(2), defines a "legally incapacitated person" as follows:

[A] person ... who is impaired by reason of mental illness, mental deficiency, physical illness or disability, chronic use of drugs, chronic intoxication, or other cause, to the extent that the person lacks sufficient understanding capacity to make or communicate informed decisions concerning his or her person.
We express no opinion regarding whether Richard also falls within this definition of a legally incapacitated person.
[3]  The Legislature has amended this definition, effective March 28, 1996, to read as follows:

"Developmental disability" means either of the following:
(a) If applied to an individual older than 5 years, a severe, chronic condition that meets all of the following requirements:
(i) Is attributable to a mental or physical impairment or a combination of mental and physical impairments.
(ii) Is manifested before the individual is 22 years old.
(iii) Is likely to continue indefinitely.
(iv) Results in substantial functional limitations in 3 or more of the following areas of major life activity:
(A) Self-care.
(B) Receptive and expressive language.
(C) Learning.
(D) Mobility.
(E) Self-direction.
(F) Capacity for independent living.
(G) Economic self-sufficiency.
(v) Reflects the individual's need for a combination and sequence of special, interdisciplinary, or generic care, treatment, or other services that are of lifelong or extended duration and are individually planned and coordinated. [M.C.L. § 330.1100a(19); M.S.A. § 14.800(100a)(19).]
[4]  Richard has been clinically diagnosed as being mildly mentally retarded. He cannot read, write, or dial a telephone. He can do only the simplest of arithmetic and is unable to carry out monetary transactions except in single dollar amounts. He cannot pay his monthly expenses without assistance and is unable to make medical decisions for himself such as when to see a doctor or dentist. Although he is capable of learning and keeping a simple daily routine, his mental retardation renders him unable to comprehend the long-term consequences of his decisions and precludes him from performing normally in society.
[5]  Although the guardianship provisions of chapter 6 of the Mental Health Code are virtually identical to the provisions of article 4 of the Revised Probate Code in several respects, in certain areas the provisions of chapter 6 of the Mental Health Code appear to be more stringent. For example, the Mental Health Code requires that a petition for guardianship for a developmentally disabled person must be accompanied by a report that contains (1) a description of the person's developmental disability, (b) current evaluations of the person's mental, physical, social, and educational condition, adaptive behavior, and social skills, (c) an opinion whether guardianship is needed, the type and scope of the guardianship, and the reasons for the guardianship, (d) a recommendation concerning appropriate rehabilitation and living arrangements, (e) the signatures of those who performed the evaluations, one being a physician or psychologist who is competent in evaluating persons with developmental disabilities, and (f) a list of the person's medications. M.C.L. § 330.1612; M.S.A. § 14.800(612). Although the Revised Probate Code provides for the creation of a similar report, preparation and submission of the report is not mandatory; rather, the Revised Probate Code leaves the preparation of the report to the discretion of the probate court. M.C.L. § 700.443(3), (4), (5); M.S.A. § 27.5443(3), (4), (5).

When appointing a guardian pursuant to the Mental Health Code, the probate court is required to make specific findings on the record with regard to the nature and extent of the person's impairment, the person's capacity to care for himself, the person's ability to manage his financial affairs, and the appropriateness of the proposed living arrangement. M.C.L. § 330.1618; M.S.A. § 14.800(618). The Revised Probate Code contains no such requirement. Furthermore, any limited guardianship established for developmentally disabled persons must be substantially and specifically limited in scope only to the extent necessitated by the individual's actual mental and adaptive limitations. M.C.L. § 330.1602; M.S.A. § 14.800(602). To this end, the probate court must specifically define the powers and duties of the guardian. Id.; M.C.L. § 330.1618; M.S.A. § 14.800(618) and M.C.L. § 330.1620; M.S.A. § 14.800(620).
Other provisions contained in chapter 6 of the Mental Health Code are arguably less stringent than article 4 of the Revised Probate Code. Under article 4 of the Revised Probate Code, if a legally incapacitated person indicates a preference to have a particular person appointed as guardian, the probate court must appoint that designee unless the person is unsuitable or unwilling to serve as guardian. M.C.L. § 700.454(2); M.S.A. § 27.5454(2). However, under chapter 6 of the Mental Health Code, the probate court need only give "due consideration" to the developmentally disabled person's preference regarding the person to be appointed guardian. M.C.L. § 330.1628(2); M.S.A. § 14.800(628)(2).
