R. A. B. was adjudicated delinquent upon findings that he unlawfully entered a dwelling and committed a second-degree grand theft therein. The homeowner testified that he found his house broken into and property missing. The only other evidence presented was the juvenile’s confession.

R. A. B. first contends that his confession should have been suppressed, because the *17State did not establish that he, prior to confessing, was given Miranda warnings. In the context of this case, that contention presents two issues — first, were Miranda warnings required; second, were they shown to have been given.

The juvenile confessed in the office of Mr. Paroti, the administrator of Boys Town. The confession was made in the presence of Paroti and a Detective Reese. The juvenile, suspected of committing the crimes with which he was later charged, was questioned by both Paroti and Reese. Paroti testified that the juvenile had been, as of the date of the confession, in the temporary custody of Boys Town for eight months. We judicially note that Boys Town is a privately funded institution. While it is possible that the Department of Health and Rehabilitative Services has, on occasion, placed juveniles in this facility, the circumstances under which R. A. B. was lodged in Boys Town are not reflected in this record, and we will not speculate that he was there under some court order as a result of some prior juvenile offense.

In the absence of a showing that R. A. B. was, at the time of his confession, in the custody of Boys Town because of a prior and unrelated juvenile offense, he is not entitled to the benefits of the Florida Supreme Court’s holding in Young v. State, 234 So.2d 341 (Fla. 1970), which, following Mathis v. United States, 391 U.S. 1, 88 S.Ct. 1503, 20 L.Ed.2d 381 (1968), makes quite clear that where a person suspected of committing an offense is in custody, albeit for an unrelated offense,1 he is entitled to Miranda warnings prior to being questioned.2

But the inapplicability of the per se Mathis-Young rule does not end the inquiry if, in fact, it is shown that that interrogation itself was custodial. The burden of making that showing was R. A. B.’s3 and no such showing was made. The record does not reflect how R. A. B. was called or came to be in Paroti’s office. The office itself (described as containing a door, two windows, three chairs, a desk, and a cabinet) does not suggest a custodial atmosphere. There is no showing that any pressure was exerted upon R. A. B. to remain during the questioning or even what part of the questioning was done by Paroti and what part by Detective Reese. The meeting during which the confession was taken concluded in thirty minutes. In short, there is nothing to indicate that the juvenile did not voluntarily go to Paroti’s office, or that once there he was not free to leave, or even that he held such a belief. We conclude, therefore, that R. A. B. was not entitled to Miranda warnings, and his confession was admissible in the absence of such warnings.4

*18R. A. B.’s second point on this appeal is that even if the finding that he committed delinquent acts be affirmed, the order of adjudication must be reversed and the cause remanded to the trial court for a new determination whether adjudication should be entered or withheld. This point is well taken.

We have no difficulty concluding that the trial court’s decision to adjudicate R. A. B. a delinquent was based upon the impermissible consideration that the juvenile had asserted his Fifth Amendment right to remain silent, and his concomitant rights to plead not guilty and to have the State prove his guilt beyond a reasonable doubt at a trial. In explaining its decision to adjudicate R. A. B. a delinquent, the trial court stated:

“I think he was going to tell the truth. Had he come in and told me the same thing he told Mr. Paroti, I would have withheld adjudication and he could have been put on probation.

“You know my procedure and you know he could have admitted and not had a delinquency record.”

The law is clear that a court cannot, as the court did here, impose a penalty which unnecessarily discourages the assertion of such rights. McEachern v. State, 388 So.2d 244 (Fla. 5th DCA 1980); Gillman v. State, 373 So.2d 935 (Fla. 2d DCA 1979); Thomas v. United States, 366 F.2d 941 (5th Cir. 1966). See also Weathington v. State, 262 So.2d 724 (Fla. 3d DCA 1972). The very fact of adjudication, apart from disposition, has potential collateral effects which are not harmless. See, e. g., § 39.032(2)(d)4, Fla. Stat. (1980) (prior adjudication taken into account in detention decision); § 39.-09(2)(c)7c, Fla.Stat. (1980) (prior adjudication taken into account in waiver determination); see also Masci v. State, 397 So.2d 984 (Fla. 3d DCA 1981).

Accordingly, the finding that R. A. B. committed the delinquent acts charged is affirmed, and the order adjudicating him delinquent is reversed. The cause is remanded to the trial court for a new determination whether to withhold adjudication *19under Section 39.10(2), Florida Statutes (1980), or to enter an order of adjudication under Section 39.10(3), Florida Statutes (1980). Since the trial judge who adjudicated R. A. B. no longer serves on the court, it is unnecessary to order that the matter be assigned to a different judge.

Affirmed in part; reversed in part, and remanded with directions.